[FFmpeg-user] an issue on decoding a mxf xavc long gop file.

Yufei He yhe at matrox.com
Mon Apr 8 19:56:00 EEST 2019


On 04/07/2019 05:37 PM, Carl Eugen Hoyos wrote:
> 2019-04-05 17:03 GMT+02:00, Yufei He <yhe at matrox.com>:
>> On 04/05/2019 09:44 AM, Carl Eugen Hoyos wrote:
>>
>> 2019-04-04 20:06 GMT+02:00, Yufei He
>> <yhe at matrox.com><mailto:yhe at matrox.com>:
>>
>>
>> Hi
>>
>> I'm trying to trancode a 1080i xavc long gop mxf file with my
>> codec, the file's frame rate is 29.97.
>>
>> In my decoder, avctx->framerate.den is 1001, avctx->framerate.num
>> is 15000.
>>
>> This is wrong.
>>
>>
>>
>> I tested the following:
>> $ ffmpeg -i m2641080i30m25.xavc.mxf -qscale 2 -vcodec mpeg4 out.mov
>>
>> The output file plays both audio and video for 3:53 secondes (+/- 0:01).
>> This seems correct to me, no?
>>
>> Carl Eugen
>>
>> Hi Carl
>>
>> Yes, it works without using my codec.
>>
>> But it has error on debugging with my codec.
>>
>> [cid:part1.1295D7D8.8D499E95 at matrox.com]
> Please fix your quoting and please do not attach
> screen-shots, there may be exceptions but a
> large debug window probably never is.
OK.
>> I use avctx->framerate in my codec.
> Why?
>
> I am not claiming that there is no bug (I opened a ticket)
> but I don't see why you need the value, even more so
> if there is not issue with the native decoder.
The chip needs frame rate to be initialized properly.
>
>>  From the picture above, you can see framerate->num
>> is 15000, framerate->den is 1001. framerate->num
>> should be 30000.
> If you already know what the issue is, I suggest you
> send a patch (made with git format-patch, sent to
> ffmpeg-devel) to fix it.
>
> Sorry, Carl Eugen
OK, I'll try to fix it.
Regards.
Yufei.
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