WO2018107346A1

WO2018107346A1 - Usb-based data transmission method and system thereof

Info

Publication number: WO2018107346A1
Application number: PCT/CN2016/109550
Authority: WO
Inventors: 韩俊鹏; 强飞莉
Original assignee: 天彩电子（深圳）有限公司
Priority date: 2016-12-13
Filing date: 2016-12-13
Publication date: 2018-06-21

Abstract

The present invention relating to a USB-based data transmission method and a system thereof. The method comprises: defining transmission priorities of different data; sequentially transmitting video data in a defined order of high priority, medium priority, and low priority; counting the data which are being transmitted currently, and calculating the instantaneous bandwidth demands of various channels; and carrying out corresponding adjustments to the transmission loads and bandwidths of different channels. By means of predefining the transmission priorities of different data, different types of data transmission are performed according to the different transmission priorities; moreover, the loads and bandwidths of different channels are adjusted to achieve the transmission of real-time ultra-high-definition audio and video data, and also transmit multi-path high-definition audio and video data simultaneously. During the transmission of the audio and video data, communication control, state information exchange, file upload and download operations of both sides of the communication are achieved, thus facilitating a user expanding custom communication functions.

Description

USB-based data transmission method and system thereof

Technical field

The present invention relates to the technical field of video transmission, and more particularly to a USB-based data transmission method and system thereof.

Background technique

At present, the connection between various consumer Cameras and smart phones mainly uses Wi-Fi for video image data transmission, and mainly uses Wi-Fi/BLE/BT interfaces to implement an interactive control protocol framework between Camera and smart phones. Wireless interfaces such as Wi-Fi/BLE/BT are commonly used in smartphones and consumer Camera products, and the excellent user experience and compatibility of wireless network access methods make these interfaces a device in the consumer industry. The factual standard of interfacing. In PC and industrial applications, in order to simplify the docking of Camera and PC-like devices, the USB interface and UVC protocol are generally adopted to realize the application requirements of real-time reading of Camera video stream. As a USB video transmission solution defined and promoted by the USB Association, UVC is very popular in low-resolution and low-cost cameras. It can support the transmission of Camera image YUV uncompressed data, and in the 1.5 version of its protocol. It is already supported to support the transmission of Camera's H.264 compressed images.

Low-power communication methods such as BLE/BT are not suitable for large-volume communication such as audio and video streaming because of the low data transmission speed. They are only suitable for simple command interaction and inter-device transmission of small files. Therefore, the communication and interaction control protocol framework implemented by the interface based on BLE/BT does not include the function of transmitting audio and video streams.

Although Wi-Fi wireless communication technology has developed rapidly in recent years, communication speed has been greatly improved compared with the previous ones, but in the actual application of audio and video transmission, because of its transmission bandwidth limitation (generally reliable communication bandwidth is the highest 10Mbps or so), in actual use, it is generally used to transmit video with up to 720P and optimized 1080P resolution, for ultra-high definition video (such as 4K) and multi-channel HD video that require higher resolution and image quality. Transmission is still powerless.

The UVC protocol widely used in PCs and industrial applications is still mainly for low-resolution (generally no more than 640x480 resolution) low-cost Camera applications, although its 1.5 protocol can already support the transmission of H.264 data, but still not With universal application, the high version protocol has poor compatibility on various operating systems. The biggest problem is that the UVC protocol was originally designed to be convenient and fast from a variety of low-cost USB. The real-time image is read on the Camera, and there is no option to control the Camera and other information exchanges with the Camera. The user of the protocol cannot customize the protocol.

In order to solve the above problems, it is necessary to design a USB-based data transmission method to realize real-time transmission of high-definition audio and video data, and simultaneously transmit multi-channel high-definition audio and video data, and realize communication and communication between the two parties while transmitting audio and video data. Status information exchange, file upload and download operations.

Summary of the invention

The object of the present invention is to overcome the deficiencies of the prior art and to provide a data transmission method based on USB and a system thereof.

To achieve the above objective, the present invention adopts the following technical solution: a USB-based data transmission method, including the following steps:

Define the transmission priority of different data;

Video data is sequentially transmitted in the order of defined high priority, medium priority, and low priority;

Perform statistics on the data currently being transmitted, and calculate the instantaneous bandwidth requirements of different channels;

Corresponding adjustments are made to the transmission load and bandwidth of different channels.

A further technical solution is: the step of defining a transmission priority of different data, where the transmission priority includes high priority data, medium priority data, and low priority data, where the high priority data is user operation and control Command-related exchange protocol information; medium-priority data is audio and video data transmitted in real time; low-priority data is file information uploaded and downloaded in the background.

A further technical solution is: the step of sequentially transmitting video data according to the defined high priority, medium priority, and low priority order, including the following specific steps:

Determine if there is high priority data to be transmitted;

If there is high priority data to be transmitted, the high priority data is transmitted preferentially, and the next step is entered, or if there is no high priority data to be transmitted, the process proceeds directly to the next step;

Determine whether there is medium priority data to be transmitted;

If there is medium priority data to be transmitted, the medium priority data is transmitted, and the next step is entered, or if there is no medium priority data to be transmitted, the process proceeds directly to the next step;

Determine if there is low priority data to be transmitted;

If there is low priority data to be transmitted, the low priority data is transmitted, or if there is no low priority data to be transmitted, the end step is entered.

A further technical solution is: the step of correspondingly adjusting the transmission load and bandwidth of different channels, including the following specific steps:

Determining whether the number of currently transmitted high priority data is greater than a set high priority data value;

If yes, reduce the transmission frequency and packet size of the low priority data;

If not, the transmission frequency and packet size of the low priority data are increased.

A further technical solution is: if the medium priority data needs to be transmitted, the medium priority data is transmitted, and the next step is entered, or if there is no medium priority data to be transmitted, the process proceeds directly to the next step. If the medium priority data needs to be transmitted, before the step of transmitting the medium priority data, the method further includes:

Time stamping of input and output real-time audio data and video data.

A further technical solution is: the step of managing the time stamp of the input and output real-time audio data and the video data, including the following specific steps:

Sorting the sequential transmission of audio and video data according to the timestamp of encoding the audio and video data;

The timestamp is sent to the downstream link, and the downstream link uses the timestamp for data synchronization.

The invention also provides a USB-based data transmission system, comprising a defining unit, a scheduling unit, a management unit and an adjusting unit;

The definition unit is configured to define a transmission priority of different data;

The scheduling unit is configured to sequentially transmit video data according to a defined high priority, medium priority, and low priority order;

The management unit is configured to perform statistics on data currently being transmitted, and calculate an instantaneous bandwidth requirement of each different channel;

The adjusting unit is configured to perform corresponding adjustment on transmission load and bandwidth of different channels.

The further technical solution is that the scheduling unit includes an advanced judging module, an advanced data transmission module, an intermediate judging module, an intermediate data transmission module, a low-level judging module, and a low-level data transmission module;

The advanced determining module is configured to determine whether high priority data needs to be transmitted;

The advanced data transmission module is configured to preferentially transmit high priority data;

The intermediate level determining module is configured to determine whether medium priority data needs to be transmitted;

The intermediate data transmission module is configured to transmit medium priority data;

The low-level judging module is configured to determine whether low-priority data needs to be transmitted;

The low-level data transmission module is configured to transmit low-priority data.

A further technical solution is that the adjustment unit includes a quantity determination module and a processing module;

The quantity determining module is configured to determine whether the quantity of the currently transmitted high priority data is greater than the set high priority data value;

The processing module is configured to reduce the sending frequency and the packet size of the low priority data, or to increase the sending frequency and the packet size of the low priority data.

A further technical solution is that the adjustment unit further comprises an audio and video synchronization block for managing time stamps of the input and output real-time audio data and video data.

The beneficial effects of the present invention compared with the prior art are: a USB-based data transmission method of the present invention, by pre-defining the transmission priority of different data, and performing different types of data transmission according to different transmission priorities, and simultaneously Different channels are used to adjust the load and bandwidth to realize real-time transmission of high-definition audio and video data, and simultaneously transmit multi-channel high-definition audio and video data. At the same time of transmitting audio and video data, control communication, status information exchange, file upload and download operations are realized. It is convenient for users to customize the communication function.

The invention is further described below in conjunction with the drawings and specific embodiments.

DRAWINGS

1 is a flow chart of a USB-based data transmission method according to an embodiment of the present invention;

2 is a specific process block diagram for sequentially transmitting video data according to a defined high priority, medium priority, and low priority sequence according to a specific embodiment of the present invention;

3 is a specific process block diagram of adjusting corresponding transmission load and bandwidth of different channels according to an embodiment of the present invention;

4 is a specific flow chart of managing time stamps of input and output audio data and video data according to an embodiment of the present invention;

FIG. 5 is a structural block diagram of a USB transmission connection between a Camera device and a PC device according to an embodiment of the present invention; FIG.

FIG. 6 is a structural block diagram of a USB transmission connection between a Camera device and an Android device according to an embodiment of the present invention;

7 is a structural block diagram of a USB transmission connection between a Camera device and an iPhone/iPad device according to an embodiment of the present invention;

FIG. 8 is a structural block diagram of a USB-based data transmission system according to an embodiment of the present invention; FIG.

FIG. 9 is a structural block diagram of a scheduling unit according to an embodiment of the present invention;

FIG. 10 is a structural block diagram of an adjustment unit according to an embodiment of the present invention;

FIG. 11 is a structural block diagram of an audio and video synchronization module according to an embodiment of the present invention.

detailed description

In order to more fully understand the technical content of the present invention, the technical solutions of the present invention are further described and illustrated in conjunction with the specific embodiments, but are not limited thereto.

As shown in FIG. 1 to FIG. 11 , the USB-based data transmission method provided in this embodiment can be used for real-time transmission of different types of data between the Camera and the PC/smartphone, including but not limited to various consumptions. Class Camera, VR Camera, industrial camera, etc., realize real-time transmission of high-definition audio and video data, and transmit multiple high-definition audio and video data at the same time, realize the control communication, status information exchange, file upload and download operations of both parties while transmitting audio and video data.

As shown in FIG. 1, a USB-based data transmission method includes the following steps:

S1, defining a transmission priority of different data;

S2. sequentially transmitting video data according to the defined high priority, medium priority, and low priority order;

S3. Perform statistics on data currently being transmitted, and calculate instantaneous bandwidth requirements of different channels;

S4. Perform corresponding adjustment on transmission load and bandwidth of different channels.

In the above step S1, the step of defining a transmission priority of different data, the transmission priority includes high priority data, medium priority data, and low priority data.

The high priority data here is the exchange protocol information related to the user operation control command; the medium priority data is the audio and video data transmitted in real time; the low priority data is the file information uploaded and downloaded in the background.

Because of the diversity of transmission data types, the amount of data communicated and the different types of communication data have different requirements for real-time transmission, transmission speed, transmission bandwidth, etc., in the specific transmission, although the same communication channel is used, However, for different priority data, logical channels of different priorities are defined for transmitting the type of data, for example, three priorities of high, medium, and low on the logical channel, and if there is high priority data, the first High priority data is transmitted on high priority channels, and so on.

Further, as shown in FIG. 2, in step S2, the steps of sequentially transmitting video data in the order of defined high priority, medium priority, and low priority include the following specific steps:

S21. Determine whether high priority data needs to be transmitted;

S22. If high priority data needs to be transmitted, the high priority data is preferentially transmitted, and the process proceeds to step S23, or if there is no high priority data to be transmitted, the process directly proceeds to step S23.

S23. Determine whether there is medium priority data to be transmitted;

S24. If medium priority data needs to be transmitted, manage time stamps of input and output real-time audio data and video data;

S25: transmitting the priority data, and proceeding to step S26, or if there is no medium priority data to be transmitted, proceeding directly to step S26;

S26. Determine whether there is low priority data to be transmitted.

S27. If low priority data needs to be transmitted, the low priority data is transmitted or if there is no low priority data to be transmitted, the end step is entered.

Further, as shown in FIG. 3, in step S24, the time stamps of the input and output real-time audio data and video data are managed to ensure accurate synchronization of audio and video data throughout the transmission process, and the S24 steps include the following steps. Specific steps:

S241. Sort the sequential transmission of the audio and video data according to the timestamp encoded by the audio and video data.

S242: Send the timestamp to the downstream link, and use the timestamp to perform data synchronization processing on the downstream link.

In the step S241, the step of sorting the sequential transmission of the audio and video data according to the timestamp for encoding the audio and video data, encoding the data by using the audio and video coding system, and generating a timestamp according to the audio and video data. The timestamp of the encoding, where the timestamp is the start time and the end time of the data encoding, and the sequential transmission of the audio and video data is sorted according to the timestamp during transmission, thereby ensuring the orderly transmission of the data and avoiding the load during the transmission. Unbalanced, resulting in a smooth synchronization process.

In the above step S242, the time stamp is sent to the downstream link, and the downstream link uses the time stamp to perform the process of data synchronization, where the downstream link includes transmitting the data.

In the above steps S21, S22, S23, S24, S25, S26 and S27, in the management and control of the USB data transmission channel, it is first determined whether there is high priority data to be transmitted, and if so, the high priority data is preferentially transmitted, such as If no, continue to judge whether there is medium priority data to be transmitted, determine low priority data in turn, and transmit low priority large file data without higher priority data transmission, which can flexibly adapt to various types of Communication requirements can not only respond to the user interaction type communication requirements, but also meet the stability of low priority large data volume transmission.

Moreover, a single input and output channel is used to transmit and receive all data, and the data types sent and received are different, and the priorities are different. For high-priority data, such as data related to user interaction, the data for low-priority data, such as background upload and download files, is sent without high-priority data to be sent.

In addition, for the step of S3, the step of calculating the instantaneous bandwidth requirement of each different channel for the data currently being transmitted is mainly for balancing management of the transmission load and bandwidth of each channel endpoint in the transmission process, so as to Each channel endpoint is scheduled to maximize bandwidth support and stability for USB transmission.

Further, as shown in FIG. 4, in step S4, the steps of adjusting the transmission load and bandwidth of different channels include the following specific steps:

S41. Determine whether the quantity of the currently transmitted high priority data is greater than the set high priority data value.

S42. If yes, reduce the sending frequency and packet size of the low priority data.

S43. If not, increase the transmission frequency and packet size of the low priority data.

The step S41 is for determining whether the current high priority data is more, and adjusting according to the result of the judgment.

In step S42, when the current high priority data is large, the transmission frequency and the packet size of the low priority data are reduced, thereby improving the real-time performance of the high priority data transmission and reception.

Conversely, the transmission frequency and packet size of the low priority data are increased, that is, the high priority data is first transmitted first, and the low priority data can be transmitted in the background using a reasonable bandwidth as much as possible.

If the data transmitted at both ends of the communication contains many different types: control and status information, real-time Live Streaming data, file upload and download, etc., in the process of communication, different ways of processing and response can be made according to different types of data.

The above data transmission method is completed based on USB, and considering the unidirectionality of USB endpoint communication, at least two sets of endpoints are needed for two-way communication to realize two-way full-duplex communication, that is, Host and USB communication. The Device side needs at least one input endpoint and one output endpoint to communicate with the output endpoint and the input endpoint of the other end. The specific communication protocol design and communication data organization can be based on different types of USB endpoints (Interrupt, Bulk, Control). , Isochronous) to select and match to adapt to different communication data transmission requirements.

Specifically, in this embodiment, the Camera is used as the Device end (drive end) of the USB communication, and the PC/smartphone accesses the Camera device as the Host end (active end) of the USB communication, USB The communication and protocol implementation on the Device side is mainly carried out on the Camera, and USB The communication and protocol implementation on the Host side is mainly placed on the PC, smart phone APP (Android, iOS), etc. Both of them interact with other parts of the whole system through control information and audio and video input and output.

Further, for the connection with PC, Android mobile phone, iPhone, etc., in the implementation of the specific scheme, the audio and video streaming media data and the transmission protocol framework for controlling the interactive information are encapsulated in the interface API library of the respective platforms, which is convenient for the third-party application. The manufacturer implements streaming media data reading and control of the Camera based on the interface API.

As shown in Figure 5, when the Camera device is connected to the USB device of the PC device, the USB of the Camera device The device is connected to the USB Host interface of the PC device, and the interface with the camera is implemented in the application by integrating the API API library of the PC end on the PC side.

As shown in Figure 6, when the Camera device is connected to the USB device of the Android device, the USB interface included in the ordinary Android phone is USB. The Device interface, so the Camera device needs to be connected to the USB interface of the Android smartphone via a USB (OTG) cable. Same through on Android In the development of the app, the interface API library of the Android side is integrated into the APP application to implement the interface with the Camera device.

As shown in Figure 7, when the Camera device is connected to a USB device such as an iPhone/iPad, the Lightning of the iPhone/iPad itself has a built-in USB. Host's interface configuration mode, designed and configured for the Lightning interface of iPhone/iPad on the interface of the Camera device, using lightning The cable can be connected to the lightning interface of devices such as iPhone/iPad. Also by iOS In the development of the app, the interface API library of the iOS side is integrated into the APP application to implement interface control with the Camera device.

This embodiment performs data transmission based on USB, and has the following advantages:

1. USB transmission has the natural high transmission bandwidth capability. USB2.0 has a maximum transmission bandwidth of 480Mbps, and USB3.0 can reach 5Gbps, which far exceeds the transmission speed that wireless transmission methods such as Wi-Fi can provide. Fully capable of meeting the application requirements of simultaneous transmission of multiple extremely high resolution compressed video, this embodiment only relies on the protocol framework of the USB underlying communication mechanism to be seamlessly compatible with different protocol versions of USB;

2. Based on the four basic communication types (Interupt, Bulk, Control, Isochronous) defined by the USB standard, it provides flexible and stable support for data communication needs of different priorities, and can transmit data with a large priority on the same communication channel. The lower-level file uploading and downloading data can also transmit a higher-priority control type interactive protocol, which is convenient for the user to perform custom communication function expansion;

3, the existence of the USB interface is very extensive, whether in the emerging consumer electronics, smart phones, VR devices, or in the traditional PC, industrial cameras and other fields, USB as a convenient use to support a wide range of data transmission interfaces are basically The standard configuration of these devices makes it possible to provide audio and video data transmission capabilities in a variety of applications;

4. For the PC device, the smart phone APP and the Camera end, the pre-defined communication protocol and the protocol extension interface are respectively implemented. Only the simple transplantation and the necessary interface implementation are needed in each communication terminal, and the entire USB video communication and control can be completed. The technology integrates functions at both ends.

In summary, the above USB-based data transmission method performs different types of data transmission according to different transmission priorities by pre-defining transmission priority of different data, and performs load and bandwidth adjustment on different channels. Realize the transmission of real-time ultra-high-definition audio and video data, and simultaneously transmit multi-channel high-definition audio and video data, realize the control communication, status information exchange, file uploading and downloading operation of both parties while transmitting audio and video data, and facilitate users to customize the communication function. .

As shown in FIG. 8 to FIG. 11 , a data transmission system based on USB provided in this embodiment includes a definition unit 10, a scheduling unit 20, a management unit 30, and an adjustment unit 40;

Defining unit 10 for defining a transmission priority of different data;

The scheduling unit 20 is configured to sequentially transmit video data according to the defined high priority, medium priority, and low priority order;

The management unit 30 is configured to perform statistics on data currently being transmitted, and calculate an instantaneous bandwidth requirement of each different channel;

The adjusting unit 40 is configured to perform corresponding adjustments on transmission loads and bandwidths of different channels.

Further, the scheduling unit 20 includes an advanced judging module 21, an advanced data transmission module 22, an intermediate judging module 23, an intermediate data transmission module 25, a low-level judging module 26, and a low-level data transmission module 27;

The advanced judging module 21 is configured to determine whether high priority data needs to be transmitted;

The advanced data transmission module 22 is configured to preferentially transmit high priority data;

The intermediate judging module 23 is configured to determine whether there is medium priority data to be transmitted;

The intermediate data transmission module 25 is configured to transmit medium priority data;

The low-level judging module 26 is configured to determine whether low-priority data needs to be transmitted;

The low-level data transmission module 27 is configured to transmit low priority data.

Specifically, the adjustment unit 40 includes a quantity determination module 41 and a processing module 42;

The quantity determining module 41 is configured to determine whether the quantity of the currently transmitted high priority data is greater than the set high priority data value;

The processing module 42 is configured to reduce the transmission frequency and the packet size of the low priority data, or to increase the transmission frequency and the packet size of the low priority data.

In addition, the scheduling unit 20 includes an audio and video synchronization module 24 for managing time stamps of the input and output real-time audio data and video data.

Specifically, the audio and video synchronization module 24 includes a sorting module 241 and a synchronization sub-module 242, and is configured to sort the sequential transmission of the audio and video data according to the timestamp of encoding the audio and video data; The module 242 is configured to send the time stamp to the downstream link, and the downstream link uses the time stamp to perform the data synchronization process.

In the above USB-based data transmission system, the transmission priority of different data is predefined by the definition unit 10, and the scheduling unit 20 performs different types of data transmission according to different transmission priorities, and the management unit 30 and the scheduling unit 20 combine. Load and bandwidth adjustment for different channels, real-time transmission of high-definition audio and video data, simultaneous transmission of multi-channel high-definition audio and video data, simultaneous transmission of audio and video data, control communication, status information exchange, file upload and download Operation, convenient for users to customize the communication function expansion.

The above technical description of the present invention is further described by way of example only, and is not to be understood by the reader, but the embodiments of the present invention are not limited thereto, and any technology extending or re-creating according to the present invention is subject to the present invention. protection of. The scope of the invention is defined by the claims.

Claims

A USB-based data transmission method, comprising the steps of:

Define the transmission priority of different data;

Video data is sequentially transmitted in the order of defined high priority, medium priority, and low priority;

Perform statistics on the data currently being transmitted, and calculate the instantaneous bandwidth requirements of different channels;

Corresponding adjustments are made to the transmission load and bandwidth of different channels.
The USB-based data transmission method according to claim 1, wherein the step of defining a transmission priority of different data includes high priority data, medium priority data, and low priority Level data, the high priority data is the exchange protocol information related to the user operation and the control command; the medium priority data is the audio and video data transmitted in real time; and the low priority data is the file information uploaded and downloaded in the background.
The USB-based data transmission method according to claim 2, wherein the step of sequentially transmitting the video data in the order of the defined high priority, medium priority, and low priority includes the following specific steps:

Determine if there is high priority data to be transmitted;

If there is high priority data to be transmitted, the high priority data is transmitted preferentially, and the next step is entered, or if there is no high priority data to be transmitted, the process proceeds directly to the next step;

Determine whether there is medium priority data to be transmitted;

If there is medium priority data to be transmitted, the medium priority data is transmitted, and the next step is entered, or if there is no medium priority data to be transmitted, the process proceeds directly to the next step;

Determine if there is low priority data to be transmitted;

If there is low priority data to be transmitted, the low priority data is transmitted, or if there is no low priority data to be transmitted, the end step is entered.
The USB-based data transmission method according to claim 3, wherein the step of adjusting the transmission load and bandwidth of different channels comprises the following specific steps:

Determining whether the number of currently transmitted high priority data is greater than a set high priority data value;

If yes, reduce the transmission frequency and packet size of the low priority data;

If not, the transmission frequency and packet size of the low priority data are increased.
The USB-based data transmission method according to any one of claims 1 to 4, wherein if the medium priority data needs to be transmitted, the medium priority data is transmitted, and the process proceeds to the next step, or If there is no medium priority data to be transmitted, go directly to the next step, if the medium priority data needs to be transmitted, before the step of transmitting the medium priority data, the method further includes:

Time stamping of input and output real-time audio data and video data.
The USB-based data transmission method according to claim 5, wherein the step of managing the timestamp of the input and output real-time audio data and the video data comprises the following specific steps:

Sorting the sequential transmission of audio and video data according to the timestamp of encoding the audio and video data;

The timestamp is sent to the downstream link, and the downstream link uses the timestamp for data synchronization.
A USB-based data transmission system, comprising: a definition unit, a scheduling unit, a management unit, and an adjustment unit;

The definition unit is configured to define a transmission priority of different data;

The scheduling unit is configured to sequentially transmit video data according to a defined high priority, medium priority, and low priority order;

The management unit is configured to perform statistics on data currently being transmitted, and calculate an instantaneous bandwidth requirement of each different channel;

The adjusting unit is configured to perform corresponding adjustment on transmission load and bandwidth of different channels.
The USB-based data transmission system according to claim 7, wherein the scheduling unit comprises an advanced judgment module, an advanced data transmission module, an intermediate judgment module, an intermediate data transmission module, a low-level judgment module, and low-level data transmission. Module

The advanced determining module is configured to determine whether high priority data needs to be transmitted;

The advanced data transmission module is configured to preferentially transmit high priority data;

The intermediate level determining module is configured to determine whether medium priority data needs to be transmitted;

The intermediate data transmission module is configured to transmit medium priority data;

The low-level judging module is configured to determine whether low-priority data needs to be transmitted;

The low-level data transmission module is configured to transmit low-priority data.
The USB-based data transmission system according to claim 8, wherein the adjustment unit comprises a quantity determination module and a processing module;

The quantity determining module is configured to determine whether the quantity of the currently transmitted high priority data is greater than the set high priority data value;

The processing module is configured to reduce the sending frequency and the packet size of the low priority data, or to increase the sending frequency and the packet size of the low priority data.
A USB-based data transmission system according to claim 9, wherein said adjustment unit further comprises an audio and video synchronization block for managing time stamps of the input and output real-time audio data and video data.