EP0580638A1

EP0580638A1 - Process for compatible transmission of a signal-type additional information

Info

Publication number: EP0580638A1
Application number: EP92907677A
Authority: EP
Inventors: Andreas Ebner; Klaus Schuster; Martin Plantholt
Original assignee: Telefunken Fernseh und Rundfunk GmbH
Current assignee: Deutsche Thomson oHG
Priority date: 1991-04-18
Filing date: 1992-04-09
Publication date: 1994-02-02
Also published as: FI107491B; PL168178B1; CN1066358A; EP0509390A1; FI934571A0; JPH06506801A; CN1103530A; HU9302722D0; FI934571A; JP3297437B2; HUT66441A; MY114225A; TR28039A; BR9205914A; WO1992019072A1; CN1038176C; KR100224509B1; HU220405B

Abstract

Pour l'insertion compatible d'un format boîte aux lettres 16:9 dans des standards de télévision 4:3 existants, l'information d"image de l"enregistrement 16:9 est représentée par des bandes noires dans la partie inférieure et dans la partie supérieure de l'image. Pour la représentation plein format sur un récepteur 16:9, des informations additionnelles qui améliorent la qualité de l'image sont transmises dans les bandes noires résultant de la transmission compatible 4:3. Un code adéquat pour le type de signal est nécessaire pour qu'un récepteur 16:9 puisse correctement décoder les signaux de télévision. Pour éviter qu'une modification ou une altération de l'occupation de l'intervalle d'interruption verticale telle qu'elle était jusque-là, une information additionnelle relative au type de signal est transmise dans au moins une ligne par image complète dans les moitiés de la première ou de la dernière ligne d'image active du signal de télévision qui ne contiennent aucun signal d'image ou dans la région du palier du noir. Le signal de code peut être une giclée de signaux couleurs qui commence plus tôt et/ou finit plus tard et/ou un signal de données qui succède à ladite giclée de signaux de couleurs ou qui coincide avec celle-ci.For the compatible insertion of a 16:9 letterbox format into existing 4:3 television standards, the picture information of the 16:9 recording is represented by black bands in the lower part and in the the upper part of the image. For full format representation on a 16:9 receiver, additional information which improves the picture quality is transmitted in the black bands resulting from the 4:3 compatible transmission. The correct code for the type of signal is needed for a 16:9 receiver to correctly decode television signals. To prevent a modification or alteration of the occupation of the vertical interrupt interval as it was until then, additional information relating to the type of signal is transmitted in at least one line per complete image in the halves of the first or last active picture line of the television signal which contain no picture signal or in the black plateau region. The code signal may be a color signal burst which begins earlier and/or ends later and/or a data signal which succeeds or coincides with said color signal burst.

Description

Method for the compatible transmission of additional signal type information

The invention relates to a method for the compatible transmission of additional signal type information in lines of a television signal.

State of the art

For the compatible transmission of a color television signal in widescreen format 16: 9 with conventional number of lines and field frequency (future PALplus standard), it is known to obtain three lines from four successive lines by interpolation, which in conventional television receivers with the 4: 3 image format as a so-called letterbox Signal can be played back. So that the widescreen receiver can regenerate the original color television signal from the received letterbox signal, additional digital information must be transmitted for it in the letterbox strips, which relate to the original image content. Since both conventional and letterbox signals are transmitted on existing fine viewing channels at least in a transition period, each signal type must be identifiable by a suitable identifier. Other identifiers relate to the origin of the source signal (video camera or film scanner) and a statement about the presence of movements in the image content. Corresponding identification signals (status bits) must be transmitted as additional signal type information.

Since all the additional signal type information mentioned (PALplus additional information) is exactly correlated with the associated image content, it must be transmitted in a rigidly coupled manner with the image signal. However, with the current PAL standard, there are no free lines available in the vertical blanking interval. For example, in Germany the line no. 16 (data line) with VPS signals and others, internal radio control signals occupied. Lines 17, 18 and 19 are assigned test signals. Teletext is transmitted in lines 11 to 15 and 20 to 21. Line 22 is reserved for signal-to-noise measurements. Other bends are used in other European countries. In view of the synchronization properties of older television receivers, lines 1 to 10 cannot (yet) be assigned additional signals.

invention

The invention has for its object to provide ways of transmitting additional signal type information without changing or impairing the previous occupancy of the vertical blanking interval. This object is achieved by the method specified in claims 1 and 4.

A 16: 9 receiver for letterbox signals (PALplus receiver) should be compatible between the following compatible

Differentiate between TV signal types:

a) standard signals;

b) letterbox signals without additional information;

c) letterbox signals with additional information;

d) source signal from interlace scan (camera);

e) source signal from film scanning ('progressive' original); f) Static or dynamic image content.

In order to make this decision safely and to be able to select decoding and reproduction accordingly, it is advantageous if an appropriate identifier is transmitted on the transmitter side. This signal type identifier should be uniform across Europe. Such a signal type identifier can advantageously be transmitted in a compatible manner at locations in the CVBS signal that are used equally regardless of the respective standard. In principle, the method according to the invention consists in that for the compatible transmission of additional signal type information (16) in lines of a television signal

either:

this additional signal type information is formed from a data packet with run-in, start and useful information data, the run-in information data being used at the receiving end for the correct recovery of the data clock of the useful information data and the start information data serving for addressing the useful information data and for selectively recording the start of the useful information data and the data packet is transmitted in the half of the first or last active picture line of the television signal free of picture signals, the line half occupied with data being selected in improved 16: 9 receivers and the signal type additional information contained therein being evaluated,

or:

an identification signal is added to the television signal in the area of the rear porch in at least one line per frame before transmission and / or storage and the signal type additional information contained therein is evaluated in improved 16: 9 receivers,

in which :

the additional signal type information comprises at least two of the following television signal types:

- standard signal (no letterbox, no additional information);

- Letterbox signal without additional information;

- Letterbox signal from film source with additional information;

- Letterbox signal from the camera source with additional information, in particular with a distinction between image content considered static and moving. the fields or frames.

Advantageous further developments of the method according to the invention result from the associated dependent claims. drawings

Exemplary embodiments of the invention are described with the aid of the drawings. The drawings show in:

Figure 1 is a diagram for the signal assignment in the vertical blanking interval of a PAL color television signal.

2 shows a block diagram of a signal limiter stage of a 16: 9 receiver for the digital signal type additional information transmitted according to the invention;

3 shows a section of the occupancy of a television line free of image content with a conventional data signal;

4 shows a section of the occupancy of a picture-free television half line with a data signal designed according to the invention;

Fig. 5 is a block diagram of a receiver

Circuit details for error detection within the received digital signal type additional information transmitted according to the invention;

6 shows a section along a line of a known CVBS signal with transmission locations according to the invention for a signal type identifier.

embodiments

1 shows the current signal occupancy of the vertical blanking interval of the first field of a PAL color television signal in Germany, the numbers of the television lines concerned being plotted along the abscissa of the diagram. As can be seen from this, the first half of line no. 23 is intended for the assignment of the PALplus signal type data. A reflection measurement signal 101 is transmitted in line No. 10 and source data 102 are transmitted in line Mr. 16. Line No. 17 is a source check line and lines 18 and 19 are section check lines 104. Line 22 is used for section noise measurement 105 and the lines marked FT can transmit television text.

The useful information data of the PALplus signal type data 106 are structured in the form of several data packets. The first data packet is preceded by run-in information data and start information data. The incoming information data are used to recover the data clock of the useful information data in the receiver in the correct phase. For example, eight sinusoidal oscillations can be considered as run-in information data for conventional data signals, of which only three are shown in FIG. 3

Vibrations are shown. The sine waves synchronize in particular a PLL (phase locked loop) circuit in the 16: 9 receiver. The entry information data of the PALplus signal type data according to the invention will be discussed in more detail later.

The start information data serve to address the useful information data and to selectively record the start of the useful information data in the receiver. The 16: 9 receiver detects the occurrence of a fixed identifier, which is represented by the start information data. As soon as the receiver ascertains the sought identifier in the received signal, it can record and process the following useful information data in the correct phase.

The user information data are, for example, biphase-coded, which offers the advantage of simple code-inherent error protection. Furthermore, the signal is free of DC voltage, which is favorable for magnetic recording. To increase error protection, the useful information data can be transmitted with increased redundancy, for example in such a way that each non-inverted and inverted signal form of each data packet is transmitted sequentially, as will be explained with reference to FIG. 5. Fig. 2 shows the schematic structure of the signal limiter stage of a receiver for the PALplus signal type data. The limiter 23 receives a video signal 201 at its analog input, which receives PALplus signal type data signals in the time sections provided for this purpose. The incoming video signal is compared in the limiter 23 with a reference voltage Uref, which is present at a second input of the limiter 23. The limiter generates a "digital" random signal from the image signal component of the incoming video signal, which signal is suppressed in the subsequent evaluation. Only the data signal portion processed by the limit 23 in the incoming video signal is of interest for the evaluation. If the amplitude of the data signal contained in the video signal is greater than the reference voltage Uref, the output voltage of the digital signal output 202 corresponds to the logic state "high". If, on the other hand, the amplitude of the data signal is less than the reference voltage Uref, the output voltage of the digital signal output 202 corresponds to the logic state "low". Since the error-free limitation of the data signal depends solely on the reference voltage Uref, the careful dimensioning of the corresponding modules is particularly important. For this purpose, the video signal is also fed to a first peak voltage meter 21, which delivers the maximum signal amplitude Umax of the video signal 201 at its output with a time delay. A second peak voltage meter 22, to which the video signal 201 is also fed, operates in a similar manner. The minimum signal amplitude Umin of the video signal 201 is correspondingly delayed at the output of the second peak voltmeter 22. The best possible limitation of the data signal contained in the video signal is when the reference voltage Uref is 50% of the sum of the maximum and minimum amplitude of the video signal. The reference voltage Uref is generated by a generator 24, the inputs of which are supplied with the maximum signal amplitude Umax and the minimum signal amplitude Umin. At the output of the generator 24, the reference voltage Uref is provided, the level of which at Data signal in the steady state is (Umax + Umin) / 2.

Each time the amplitude of the video signal 201 changes, transient processes take place in the peak voltmeters 21 and 22, which are illustrated in FIG. 3 and FIG. 4 for data signals with different entry information data.

3 shows the course of the incoming information data usually used in data signals. The voltage curve of the maximum signal amplitude Umax is shown in curve A, while curve B illustrates the curve of the minimum signal amplitude Umin. Curve C shows the course of the reference voltage, which is obtained from the maximum and minimum signal voltages. It can be seen that an optimal reference voltage is only available after time period T1. Since the reference voltage determines the cutting threshold of the limiter 23, an error-free conversion into digital signals cannot be achieved during the interval T1 in the case of disturbed signal type data signals The amplitude corresponds to the umax of the data and its width comprises a multiple of the clock period of the data. The function of the first peak voltmeter 21 is influenced by this pulse in such a way that the optimum reference voltage Uref is reached after a considerably shorter time period T2. The limiter 23 of the data receiver thus works optimally at the start of the transmission of the actual incoming information data.

5 shows a simple arrangement for detecting transmission errors when evaluating serial data signals, the data packets of which are transmitted in the above-mentioned manner in non-inverted and inverted signal form. The arrangement shown contains a delay circuit 51, the signal delay T ent of the period speaks which is necessary for the transmission of a data packet. A non-inverted and an inverted signal of a data packet 501 are present at the inputs of an adder 52 downstream of the delay circuit 51 at the same time and in phase. During the transmission of related data packets, a simple error check can thus be carried out in the second half of the transmission period, since no signal occurs at the output 502 of the adder 52 during the transmission of error-free data signals. If additional error protection measures, for example biphase coding, are also implemented in the data packets, appropriate correction mechanisms can be applied when error signals occur at the output 502 of the adder 52.

FIG. 6 shows a section of a CVBS signal along a television line with a synchronous imptile 11, a burst signal 12 and an image signal 13. A first section 15 on the rear porch can receive a signal type identifier. It is also possible to superimpose the signal type identifier on the burst signal in a second section 14 or to use the first and the second section for the transmission of the signal type identifier.

The signal type identifier must meet several criteria to ensure compatibility with conventional receivers. Neither the synchronization, nor the color demodulation or the clamping of conventional receivers may be adversely affected. These boundary conditions are met if the identification signal is implemented as a digital data signal in a DC value-free coding and the data rate is lower than the color carrier frequency, e.g. 1 Mbit / s.

Due to the narrowband nature of the color PLL of conventional receivers, the color demodulation and reproduction are not adversely affected. If a standard PAL signal with letterbox strips is received by a 16: 9 receiver, the signal type identifier allows the activation of a format changeover, which results in a full-format display without letterbox strips. A simple implementation of such an identifier could, for example, result in a changed number of vibration cycles of the

Burst signals lie, the 16: 9 receiver by determining the number of oscillation trains, e.g. by counting the oscillation trains or by determining the

Burst signal length, the required information wins.

A distinction between letterbox signals with additional information is advantageous, since depending on the source (film or camera) different processing algorithms for the chrominance are provided in future 16: 9 receivers (PALplus). These types of processing can then be addressed directly via the signal type identifier.

In general, the number of letterbox lines is known, so that the recipient only minimally uses the identifier once per frame, e.g. needs to be transmitted once per field. To ensure recognition, however, an identification repeat would be desirable. The accommodation of the identification signal in the first 15 and / or second 14 section according to FIG. 6 can then advantageously take place in the vertical overscan area or even during vertical blanking.

A simple implementation option with. With the help of some additional vibrations, for example half the color carrier frequency in the first section 15 in lines of the vertical return, the following table specifies (0: line without additional vibration, 1: line with additional vibration): Line n Line n + 1 signal type

0 0 standard signal (no letterbox, none

Further information);

0 1 letterbox signal without additional information;

1 0 Letterbox signal from film source with

Further information;

1 1 Letterbox signal from camera source with

Further information.

By adding further lines, other of the above-mentioned signal types can be identified.

The signal type identifier can also be formed by identifier signals distributed over several lines per picture, whereby e.g. detection reliability in the receiver can be increased.

Cinema films transmitted with television systems can have different source picture formats. The letterbox strips are accordingly different in width. It is now also possible to include different letterbox formats in the signal type identifier and to transmit an identifier signal as a format helper. This format helper then results in the transmission of standard PAL signals with letterbox to b) a format-filling display on the 16: 9 receiver by changing the vertical deflection amplitude or using corresponding digital processing.

For recording letterbox PAL signals of type d) or e) on S-VHS or Hi8 recorders accordingly

PCT / EP91 / 00676 and DE 41 11 979 it is expedient to indicate by means of an additional signal type identifier that a previously recorded letterbox PAL signal is given to the 16: 9 receiver for display. This signal type identifier can advantageously be keyed into the composite signal after playback from the tape. This indicates to the receiver that the partial decoding performed for the recording letterbox PAL signals with additional information

PCT / EP91 / 00676 and DE 41 11 979 has already been carried out.

The solutions according to the invention for the transmission of identification signals can also be used in NTSC and SECAM systems.

Claims

1. A method for the compatible transmission of additional signal type information (16) in lines of a television signal, in which this additional signal type information is formed from a data packet with entry, start and useful information data, the receiving information data for the phase-correct recovery of the data clock of the useful information data serve and the

Start information data for addressing the useful information data and for selectively recording the start of the useful information data are used, characterized in that the data packet is transmitted in the half of the first or last active picture line of the television signal free of picture signals and in improved 16: 9 receivers the line half occupied with data is selected and the additional signal type information contained therein is evaluated, the additional signal type information comprising at least two of the following television signal types:

- standard signal (no letterbox, no additional information);

- Letterbox signal without additional information;

- Letterbox signal from film source with additional information;

- Letterbox signal from the camera source with additional information, in particular with a distinction between the static or moving image content of the fields or frames.

2. The method according to claim 1, characterized in that the entry information data is preceded by a pulse whose amplitude corresponds to the maximum level (Umax) of the data and whose width comprises a multiple of the clock period of the data.

3. The method according to claim 1 or 2, characterized in that the useful information data are sent in such a way that each data packet (501) transmits its non-inverted and inverted signal form sequentially and that the associated end is not received on the receiving side for fixing transmission errors for each inverted signal form - Inverted waveform is added (52), a resulting non-zero signal sum indicating a transmission error.

4. A method for the compatible transmission of additional signal type information in lines of a television signal, an identification signal being added to the television signal in the area of the rear porch in at least one line per frame before transmission and / or storage, and the additional signal type information contained therein in improved 16 : 9 receivers is evaluated, the additional signal type information comprising at least two of the following television signal types:

- standard signal (no letterbox, no additional information);

- Letterbox signal without additional information;

- Letterbox signal from Film-Quello with additional information;

- Letterbox signal from camera source with additional information, especially with. a distinction between the static or moving image content of the fields or frames.

5. The method according to claim 4, characterized in that the identification signal is formed by a color burst (12) which begins earlier and / or ends later.

6. The method according to claim 4 or 5, characterized in that the identification signal by a color burst (12) which begins earlier and / or ends later. and / or is formed by a data signal arranged after the color burst or coincident with the color burst.

7. The method according to one or more of claims 4 to

6, characterized in that the identification signal is present in the vertical return and / or in the vertical overscan area and / or in letterbox strips.

8. The method according to one or more of claims 4 to

7, characterized in that the identification signal is repeated several times during a frame or field.

9. The method according to one or more of claims 4 to

8, characterized in that the type of signal is indicated by identification signals distributed over several lines per image.

10. The method according to one or more of claims 1 to

9, characterized in that a DC voltage-free coding with a data rate that is lower than that of the color carrier frequency is selected for the identification signal.

11. The method according to one or more of claims 1 to

10, characterized in that the identification signal indicates different letterbox formats.

12. The method according to one or more of claims 1 to

11, characterized in that when playing letterbox television signals stored on image recorders, such an identification signal in the

Television signal is keyed in that the partial decoding of additional letterbox information already occurred during storage.