KR0175459B1 - Codec conversion device from h.261 to itu-r601 - Google Patents

Abstract

The present invention relates to a conversion apparatus for converting an H.261 video codec having a form of a common intermediate format (hereinafter, referred to as 'CIF') into an ITU-R 601 form. Is reset, the data of the luminance component is inputted from the H.261 codec in synchronization with the write clock by the write signal, stored therein, and the read process is reset by the read reset signal. First, second frame memory means (12, 13); First and second multiplexing means (10, 11) for receiving data of chromaticity components from the H.261 codec and enabling and multiplexing and outputting the data by means of an external selection signal; And a write process of the output of the first and second multiplexing means 10 and 11 is reset by a write reset signal. The write process of the first and second multiplexing means 10 and 11 is input and stored in synchronization with the write clock. And third and fourth frame memory means 14 and 15 for outputting in synchronism with the read clock by the read signal, and to output a signal of a device having a non-parallel scanning CIF image format to a TV screen. There is an effect that can be used as a video output conversion apparatus of a videoconferencing terminal using an H.261 video codec by converting to an intermediate ITU-R 601 digital common format.

Description

Converter for converting H.261 video codec having common intermediate format into ITU-R 601 format

1 is a block diagram of a converter according to an embodiment of the present invention.

2 is a timing diagram according to an embodiment of the present invention.

* Explanation of symbols for main parts of the drawings

10: first multiplexer 11: second multiplexer

12: first frame memory 13: second frame memory

14: third frame memory 15: fourth frame memory

The present invention relates to a conversion apparatus for converting an H.261 video codec having a form of a common intermediate format (hereinafter referred to as 'CIF') into an ITU-R 601 form.

The H.261 codec section, which defines the video compression / restore method in the ITU-T H series, converts these signals into ITU-R 601 signals, which are common signal standards, to input and output NTSC, PAL, SECAM, and various standards. After that, it is recommended to input / output the converted signal to CIF format again. That is, most of the H.261 codec output video configuration forms the luminance ratio Y and the chromaticity component CbCr of 4: 4: 4, and the resolution and the synchronization signal are 352 pixels × 288 lines, respectively. The vertical sync signal has a non-parallel scan format with 29.97 Hz and horizontal sync signal 15.734 KHz. Therefore, in order to convert this signal into a national standard NTSC analog signal, the signal must be converted into the ITU-R 601 common digital format including the conversion of the non-parallel scan type to the perforated scan type.

Accordingly, an object of the present invention is to provide a conversion apparatus for converting an output of an H.261 video codec having a CIF form into an ITU-R 601 form.

According to the present invention for achieving the above object, the writing process is reset by the write reset signal, and the luminance component data is inputted and stored in synchronization with the write clock by the write signal from the H.261 codec and read by the read reset signal. A first and second frame memory means for resetting the process and outputting in synchronization with the read clock by the read signal; First and second multiplexing means for receiving data of chromaticity components from the H.261 codec and enabling and multiplexing and outputting the data by using an external selection signal; And a writing process is reset by a write reset signal, the input of the first and second multiplexing means is reset by a write reset signal, is synchronized with a write clock by a write signal, and stored. The read process is reset by a read reset signal. And third and fourth frame memory means for outputting in synchronization with the read clock.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention;

1 is a block diagram of a converter according to an embodiment of the present invention, in which 10 is a first multiplexer, 11 is a second multiplexer, 12 is a first frame memory, 13 is a second frame memory, and 14 is a The third frame memory 15 denotes the fourth frame memory, respectively.

The operation of the present invention will be described with reference to FIG. 2. First, the Y component, which is a luminance component of the output signal of the H.261 codec, is input to the first and second frame memories 12 and 13 as shown in the drawing. The input pointers of the first and second frame memories 12 and 13 are reset to zero every 29,97 Hz of the vertical synchronization signal that is the write reset signal. In addition, the input Y component has a bandwidth of 6.75 Mhz of band clock, which is a write clock, in units of horizontal sync signal 15.734Khz, which is a write signal per line, and is stored in the first and second frame memories 12 and 13.

The first and second frame memories 12 and 13 for inputting the image having the luminance component have a capacity of 256K × 8 bits, and accordingly, the first and second frame memories 12 for every write reset signal 29.97 Hz. (13) stores a non-parallel scanning image of 352 pixels x 288 lines, that is, 101,376 bytes. Unlike the processing method of the Y portion, which is the luminance component, the CbCr component, which is the chromaticity portion, is multiplexed into an 8-bit signal sequence using a multiplexer to satisfy the format of the image configuration type YCbCr (4: 2: 2). That is, the first and second multiplexers 10 and 11 multiplex the CbCr component inputted from the H.261 codec into an 8-bit signal sequence by a 6.75 MHz uvsel signal, which is an external selection signal, to form a third and fourth frame memory. Output to (14, 15).

The chroma component CbCr signal, which is multiplexed into an 8-bit signal sequence through the first and second multiplexers 10 and 11, is stored in a frame memory having a capacity of 256K × 8 bits in the same manner as the processing method of the enhanced luminance component Y. The input is stored. The image of YCbCr stored in each frame memory is reset by outputting the output pointer of each frame memory 12-15 to 0 every 59.94 Hz of the vertical synchronization signal which is a read reset signal when outputted from each frame memory 12-15. By scaling 44 lines and outputting a signal scaled to 240 lines twice in succession, it is converted into a bipolar scan signal having 480 lines.

Read the YCbCr component of each frame memory (12 to 15), which is output with a bandwidth of 6.75 Mhz with a horizontal sync signal of 15.734 KHz, which is a read signal, using the double clock of 13.5 Mhz (pixclk) to read 352 pixels per line. It can be expanded to 704 pixels which is doubled.

In the present invention as described above, the output of the H.261 codec having a video configuration of 352 × 288, which is a non-parallel scanning method, has a form of 704 × 480, which is a progressive scanning method, and is converted to the ITU-R 601 common digital video format. This is done. However, if the alias is used, the number of pixels per line of the signal converted through the above process is 704, which is 16 fewer than 720 pixels per line of the ITU-R 601.

However, even though 16 pixels are actually lacking, the horizontal sync signal and the horizontal blocking signal representing the effective number of pixels per line of the sync signals representing the output image last as many as 720 pixels, so that they are converted into NTSC analog signals and output to the screen. Only the left and right 8 pixels of information per line will appear black. (In fact, 8 pixels of left and right information is negligible compared to 720 pixels in total, and there is little change in the output image.)

The video converted to the ITU-R 601 digital format using the video format converter described above can be easily converted to an NTSC analog signal using a commercially available NTSC encoder.

In order to output a signal of a device having a non-progressive scanning CIF image format to a TV screen, the present invention configured and operated as described above is converted to an ITU-R 601 digital common format, which is an intermediate step, to convert the H.261 image codec. There is an effect that can be used as a video output conversion apparatus of a video conferencing terminal.

Claims (1)

The write process is reset by the write reset signal, the data of the luminance component is inputted and stored in synchronization with the write clock by the write signal from the H.261 codec, and the read process is reset by the read reset signal. First and second frame memory means (12, 13) for outputting in synchronization with a read clock; First and second multiplexing means (10, 11) for receiving data of chromaticity components from the H.261 codec and enabling and multiplexing and outputting the data by means of an external selection signal; And a write process of the output of the first and second multiplexing means 10 and 11 is reset by a write reset signal. The write process of the first and second multiplexing means 10 and 11 is input and stored in synchronization with the write clock. And a third and fourth frame memory means (14, 15) for outputting in synchronization with a read clock by a read signal. ITU-R601 is a H.261 video codec having a form of a common intermediate format. Conversion device to convert to form.