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

Eng. Tweellt tweellt at gmail.com
Thu Feb 26 18:26:36 CET 2015

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

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"

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)) <
            return err;
    } /*else {
        if ((err = mxf_write_partition(s, 0, 2, footer_partition_key, 0)) <
            return err;

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->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 |
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?

Thanks guys,


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