[FFmpeg-devel] There may be a bug for .mp4 reader.

Yufei He yhe at matrox.com
Mon Apr 1 22:57:17 EEST 2019


On 04/01/2019 01:42 PM, Devin Heitmueller wrote:
> Hello Yufei,
>
>> On Apr 1, 2019, at 1:21 PM, Yufei He <yhe at matrox.com> wrote:
>>
>> Hi
>>
>> There may be a bug for .mp4 reader.
>>
>> On decoding some ntsc mp4 files with my h.264 codec, from actvx I received,
>>
>> avctx->framerate.den is 100
>>
>> avctx->framerate.num is 2997
>>
>> avctx->pkt_timebase.num is 1
>> avctx->pkt_timebase.den is 2997
>>
>> Duration of every packet I received from ff_decode_get_packet(avctx, &pkt) is 100, which means it's a encoded frame. But actually, it's a encoded field, it's duration should be 50.
> Libavcodec doesn’t have any support for delivering individual fields.  Decoders are expected to reassemble fields into frames before providing them back to callers.
>
> Presumably this is some sort of PAFF encoded stream?  Does it decode properly when using the software h.264 decoder?
>
> Devin
Hi Devin

The data decoded is in frames, my problem is the source compressed data: 
it could be a field or a frame depending on files, every packet for 
compressed data has duration and it should be accurate, I use it 
directly instead of parsing it again. it seems it's not correct for some 
.mp4 files. and I find it's not correct for xavc mxf long gop files 
today, though xavc intra files are good.

Yufei.
> ---
> Devin Heitmueller - LTN Global Communications
> dheitmueller at ltnglobal.com
>
>
>
>
>
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