[Libav-user] Problem with using libavcodec with AV_CODEC_ID_H264

[Harald Jordan]

Hm, i really dont believe your problem is the flushing part itself.

 

I wonder if the pkt you are sending to the encoder is initialized - at least
i cannot see how. There is a huge number of issues in avcodec_encode_video2
that occur when you send it a pkt that it did not expect.

 

Here is how I flush at the end of transcoding:

       int stillgotframes = 1;

       while(stillgotframes){

             AVPacket pkt; 

             av_init_packet(&pkt);

             int got_packet=0;

             int ret = -1;

             pkt.size = video_outbuf_size; //1000000

             pkt.data = video_outbuf; // constant location in memory

             ret = avcodec_encode_video2(video_st->codec, &pkt, NULL,
&got_packet);

             av_interleaved_write_frame(oc, &pkt);

             stillgotframes = got_packet;

       }

 

 

Harry

Von: libav-user-bounces at ffmpeg.org [mailto:libav-user-bounces at ffmpeg.org] Im
Auftrag von Ashwin Chandra - SISA
Gesendet: Friday, February 08, 2013 7:22 PM
An: This list is about using libavcodec, libavformat, libavutil, libavdevice
and libavfilter.
Betreff: Re: [Libav-user] Problem with using libavcodec with
AV_CODEC_ID_H264

 

All those presets I tried but didn't help.

 

From: libav-user-bounces at ffmpeg.org [mailto:libav-user-bounces at ffmpeg.org]
On Behalf Of Ashwin Chandra - SISA
Sent: Friday, February 08, 2013 8:39 AM
To: This list is about using libavcodec, libavformat, libavutil, libavdevice
and libavfilter.
Subject: Re: [Libav-user] Problem with using libavcodec with
AV_CODEC_ID_H264

 

But the decoding_encoding example works for me without any changes. The
problem is if you just want to encode two frames and flush them all out.
With 25 there doesn't seem to be any issues.

 

 

From: libav-user-bounces at ffmpeg.org [mailto:libav-user-bounces at ffmpeg.org]
On Behalf Of Harald Jordan
Sent: Friday, February 08, 2013 12:53 AM
To: 'This list is about using libavcodec, libavformat, libavutil,
libavdevice and libavfilter.'
Subject: Re: [Libav-user] Problem with using libavcodec with
AV_CODEC_ID_H264

 

If you did not make any changes to the open_video and add_video functions of
the decoding_encoding example, it cannot work. For H264 you need to manually
define a set a of H264 private settings before opening the codec.

http://stackoverflow.com/questions/3553003/encoding-h-264-with-libavcodec-x2
64

 

Harry

 

Von: libav-user-bounces at ffmpeg.org [mailto:libav-user-bounces at ffmpeg.org] Im
Auftrag von Ashwin Chandra - SISA
Gesendet: Freitag, 08. Februar 2013 00:29
An: This list is about using libavcodec, libavformat, libavutil, libavdevice
and libavfilter.
Betreff: Re: [Libav-user] Problem with using libavcodec with
AV_CODEC_ID_H264

 

To be clearer, I modified the decoding_encoding.c example in ffmpeg to cause
the problem.

I basically changed the video_encode_example() to encode 1 second worth of
video and then flush the delayed frame. The code below is exactly the same
except 25 frames was replaced with 1 frame.

Now if I take this code block and duplicate it again, so that it basically
runs twice, the second avcodec_encode_video2() will hang.

 

 

/* encode 1 second of video */

    for(i=0;i<1;i++) {

        av_init_packet(&pkt);

        pkt.data = NULL;    // packet data will be allocated by the encoder

        pkt.size = 0;

 

        fflush(stdout);

        /* prepare a dummy image */

        /* Y */

        for(y=0;y<c->height;y++) {

            for(x=0;x<c->width;x++) {

                frame->data[0][y * frame->linesize[0] + x] = x + y + i * 3;

           }

        }

 

        /* Cb and Cr */

        for(y=0;y<c->height/2;y++) {

            for(x=0;x<c->width/2;x++) {

                frame->data[1][y * frame->linesize[1] + x] = 128 + y + i *
2;

                frame->data[2][y * frame->linesize[2] + x] = 64 + x + i * 5;

            }

        }

 

        frame->pts = i;

 

        /* encode the image */

        ret = avcodec_encode_video2(c, &pkt, frame, &got_output);

        if (ret < 0) {

            fprintf(stderr, "Error encoding frame\n");

            exit(1);

        }

        

        if (got_output) {

            printf("Write frame %3d (size=%5d)\n", i, pkt.size);

            fwrite(pkt.data, 1, pkt.size, f);

            av_free_packet(&pkt);

        }

    }

 

    /* get the delayed frames */

    for (got_output = 1; got_output; i++) {

        fflush(stdout);

 

        ret = avcodec_encode_video2(c, &pkt, NULL, &got_output);

        if (ret < 0) {

            fprintf(stderr, "Error encoding frame\n");

            exit(1);

        }

 

        if (got_output) {

            printf("Write frame %3d (size=%5d)\n", i, pkt.size);

            fwrite(pkt.data, 1, pkt.size, f);

            av_free_packet(&pkt);

        }

    }

 

 

 

From: libav-user-bounces at ffmpeg.org [mailto:libav-user-bounces at ffmpeg.org]
On Behalf Of Ashwin Chandra - SISA
Sent: Thursday, February 07, 2013 3:08 PM
To: libav-user at ffmpeg.org
Subject: [Libav-user] Problem with using libavcodec with AV_CODEC_ID_H264

 

I have some code that takes a running stream of uncompressed video data and
encodes it using AV_CODEC_ID_H264.

 

The sequence I follow is

1.  Call avcodec_encode_video2 on the AVFrame which contains my uncompressed
frame.

2.  Call avcodec_encode_video2 again passing NULL in the AVFrame parameter.

3.  Repeat 2. Until a frame arrives from the encoder.

 

This seems to work fine if the codec is MPEG2, but with H264, it hangs
inside avcodec_encode_video2 at step 2) on the second frame. I don't have
debug symbols and can't figure out why. Does there need to be a minimum set
of uncompressed data in the encoder before trying to flush out an encoded
frame for H264? If so, how do I know when it is safe to flush a frame?

 

 

 

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