[FFmpeg-devel] Live encoding into mxf...

[Michael Niedermayer]

On Thu, Feb 26, 2015 at 05:26:36PM +0000, Eng. Tweellt wrote:
> Hello everyone,
> 
> I'm trying to encode video and audio directly from a capture board, 1 video
> stream and 8 single channel audio streams into a MXF file encoding it in
> Mpeg-2.
> 
> Everything is working fine except when I call av_write_trailer() at the end
> (and before freeing CodecContext as stated in the documentation).
> 
> After using av_write_trailer, I end up with the whole video looking like
> this http://i.imgur.com/M6HkcpR.jpg . It seems like the decoder is
> misplacing the b-frames in the wrong position, but  If i don't call this
> function I can play the media file, with the image as it should be, in VLC
> but the timestamp is completely wrong.
> Looking at mediainfo I can see that my file doesn't  have the file duration
> (which later made sense when I looked inside the code.)
> 
> After a few hours with the file mxfenc.c  found  that if I comment the next
> part inside the function mxf_write_footer(), the write trailer "kinda"
> works,
> 
> (...)
> if (mxf->edit_unit_byte_count && s->oformat != &ff_mxf_opatom_muxer) { //
> no need to repeat index
>         if ((err = mxf_write_partition(s, 0, 0, footer_partition_key, 0)) <
> 0)
>             return err;
>     } /*else {
>         if ((err = mxf_write_partition(s, 0, 2, footer_partition_key, 0)) <
> 0)
>             return err;
>         mxf_write_klv_fill(s);
>         mxf_write_index_table_segment(s);
>     }*/
> (...)
> 
> The "kinda" works part, its because I can play the file correctly in VLC
> with the correct timestamps, and if I open it with Mediainfo everything
> looks good, but If I try to open it with Sorenson Squeeze (for example), I
> get a warning saying  "Squeeze does not support playing this file".
> I carefully followed the documentation, samples, examples and I'm still
> stuck :S.
> I am using the ffmpeg 2.5.1 version and I also added a few changes that I
> saw in the master, and nothing changed.
> 
> Additional info:
> 
> Target Output file format is a 1080i59.94, XDCam 30Mbit MXF op1a.
> 
> Regarding the 8 audio streams the codec options have the one provided by
> avcodec_get_context_defaults3 plus this changes:
> 
> audio_codec_context->channels=1;
> audio_codec_context->sample_rate = 48000;
> audio_codec_context->bit_rate = 768000;
> audio_codec_context->sample_fmt =AV_SAMPLE_FMT_S16;
> audio_codec_context->flags= CODEC_FLAG_GLOBAL_HEADER;
> audio_codec_context->time_base->num = 48000;
> 
> 
> Regarding video  I also do avcodec_get_context_defaults3 plus this:
> 
> video_codec_context-> pix_fmt= AV_PIX_FMT_YUV422P;
> video_codec_context->height = 1080;
> video_codec_context->time_base->den = 30000;
> video_codec_context->time_base->num = 1001;
> video_codec_context->field_order= AVFieldOrder.AV_FIELD_TB;
> video_codec_context->width = 1920;
> video_codec_context->codec_id= AV_CODEC_ID_MPEG2VIDEO;
> video_codec_context->has_b_frames= 1;
> video_codec_context->max_b_frames = 2;
> video_codec_context->gop_size= 12;
> video_codec_context->global_quality= FF_QP2LAMBDA * 1;
> video_codec_context->rc_initial_buffer_occupancy= 10695476;
> video_codec_context->scenechange_threshold = 1000000000;
> video_codec_context->color_primaries= AVCOL_PRI_BT709;
> video_codec_context->color_trc= AVCOL_TRC_BT709;
> video_codec_context->qmin= 1;
> video_codec_context->flags |= CODEC_FLAG_GLOBAL_HEADER |
> CODEC_FLAG_INTERLACED_DCT | CODEC_FLAG_INTERLACED_ME;
> video_codec_context->bit_rate =   30000000;
> video_codec_context->rc_min_rate= 30000000;
> video_codec_context->rc_max_rate= 30000000;
> video_codec_context->rc_buffer_size= 10695476;
> 
> 
> I also had specified me_method and me_range, but nothing changed.
> 
> Any idea what might be the problem?

can the problem be reproduced with command line FFmpeg ?

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

While the State exists there can be no freedom; when there is freedom there
will be no State. -- Vladimir Lenin
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