[Ffmpeg-devel] Image blurs in case of packet loss when using h.263 codec

[Zhang Yong]

Dear all,

 

Recently, I am trying to use libavcodec to develop a network video
application under Windows. Because it is a video conferencing application, I
chose the h.263 codec, and used the UDP transport protocol to transfer the
encoded data on the network. But since UDP is not a reliable protocol,
whenever packet loss occurs, there are serious image blurs on the decoded
image of the receiver.

 

The blurred image is *attached*. I don't know whether this is an inherent
property of the h.263 codec. If so, how can I avoid image blurs in case of
packet loss? I have been tangled with this issue for about two weeks. It
will be very appreciated if anybody could help me out. Thanks.

 

The following is my code to decode frames:

 

BOOL RecvVideoWnd::decodeOneFrame(LPBYTE data, int size)

{

         int got_picture;

         int n = avcodec_decode_video(decoder, yuvFrame, &got_picture, data,
size);

         if (n < 0 || !got_picture)

                   return FALSE;

 

         img_convert((AVPicture *) rgbFrame, PIX_FMT_RGB24,

                   (AVPicture *) yuvFrame, decoder->pix_fmt,

                   videoFormat.biWidth, videoFormat.biHeight);

 

         // Repaint the receiver window

         Invalidate();

         return TRUE;

}

 

void RecvVideoWnd::onDataReceived(LPBYTE data, int size)

{

         uint8_t *outbuf;

         int outbuf_size;

         int len;

 

         while (size > 0) {

                   len = av_parser_parse(parser, decoder, &outbuf,
&outbuf_size,

                            (LPBYTE) data, size, AV_NOPTS_VALUE,
AV_NOPTS_VALUE);

                   if (outbuf_size > 0)

                            decodeOneFrame(outbuf, outbuf_size);

 

                   data += len;

                   size -= len;

         }

}

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