Re: [Libav-user] Demuxer not giving proper data to decoder ?

[Carl Eugen Hoyos]

2016-09-15 13:54 GMT+02:00 Carl Eugen Hoyos :
> 2016-09-15 13:41 GMT+02:00 ssshukla26 :
>
> [...]
>
> Did you already look at other hardware decoders in current FFmpeg?

You may be interested to see this patch on -devel:

crystalhd: Use up-to-date bsf API
http://ffmpeg.org/pipermail/ffmpeg-devel/2016-September/199734.html

Carl Eugen
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Re: [Libav-user] Demuxer not giving proper data to decoder ?

[ssshukla26]

under *./libavcodec/hevc_mp4toannexb_bsf.c* there is note as below.

When private_spspps is zero then spspps_buf points to global extradata and
bsf does replace a global extradata to own-allocated version (default
behaviour).

When private_spspps is non-zero the bsf uses a private version of spspps
buf. This mode necessary when bsf *uses in decoder*, else bsf has issues
after decoder re-initialization. Use the "*private_spspps_buf*" argument to
activate this mode.



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Re: [Libav-user] Demuxer not giving proper data to decoder ?

[ssshukla26]

Solved it by following code under *decode* function of decoder.


if(*av_bitstream_filter_filter*(decoder->bsf, avctx, "*private_spspps_buf*",
>pkt.data,
>pkt.size,
avpkt->data, avpkt->size,
!!(avpkt->flags & AV_PKT_FLAG_KEY)) < 0)
{
ERROR("Error: unable to convert data from avcc to annexb");
}
else
{
//Do decoding of decoder->pkt.data instead of avpkt->data
}



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Re: [Libav-user] Demuxer not giving proper data to decoder ?

[Carl Eugen Hoyos]

2016-09-15 13:41 GMT+02:00 ssshukla26 :

[...]

Did you already look at other hardware decoders in current FFmpeg?

Carl Eugen
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Re: [Libav-user] Demuxer not giving proper data to decoder ?

[ssshukla26]

Ok. I might be wrong, but the demuxers are only for extracting data out of
the container ! Right ?

So If that the case, any decoder will receive data in *AVCC* format when
*mp4* files are used as input ?

So one must convert data from avcc to annexb format under the decoder ? 



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Re: [Libav-user] Demuxer not giving proper data to decoder ?

[Carl Eugen Hoyos]

2016-09-15 13:30 GMT+02:00 ssshukla26 :
> But I don't understand one thing, my decoder is working properly
> with a *h264* file in proper AnnexB data format, and when using
> *mp4* file which is in AVCC format, the demuxing which should take
> place is not taking place at all !

I may misunderstand you but I (strongly) suspect it is not the
> demuxers job to mess with video data.

Again:
Please look at what other existing hardware decoders in FFmpeg do.

Carl Eugen
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Re: [Libav-user] Demuxer not giving proper data to decoder ?

[ssshukla26]

Yup. that's true.

But I don't understand one thing, my decoder is working properly with a
*h264* file in proper AnnexB data format, and when using *mp4* file which is
in AVCC format, the demuxing which should take place is not taking place at
all ! Does that mean I need to configure the demuxer with my decoder or
something like that ? 




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Re: [Libav-user] Demuxer not giving proper data to decoder ?

[Carl Eugen Hoyos]

2016-09-15 13:19 GMT+02:00 ssshukla26 :
> It runs properly, with "*h264*" (default) software decoder without using bit
> stream filter.
>
> Which makes me believe that I must be missing something in configuring
> decoder to receive proper demuxed data, but I dont know what I am missing !

Do I understand correctly that your hardware decoder only accepts
data in Annex B format, not in avcC? I suspect this is also true for
other hardware decoders already in FFmpeg, check what they do.

Carl Eugen
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Re: [Libav-user] Demuxer not giving proper data to decoder ?

[ssshukla26]

It runs properly, with "*h264*" (default) software decoder without using bit
stream filter.

Which makes me believe that I must be missing something in configuring
decoder to receive proper demuxed data, but I dont know what I am missing ! 



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Re: [Libav-user] Demuxer not giving proper data to decoder ?

[Carl Eugen Hoyos]

2016-09-15 13:10 GMT+02:00 ssshukla26 :
> I have made a custom decoder with name "*h264_qhw*" and id
> "*AV_CODEC_ID_H264*".

What happens if you test your code (without the bitstream filter)
with the existing software decoder?

Carl Eugen
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Re: [Libav-user] Demuxer not giving proper data to decoder ?

[Carl Eugen Hoyos]

2016-09-15 11:05 GMT+02:00 ssshukla26 :
> After debugging, I realized that my decoder is getting data in *AVCC*
> format, so on application side I added bit stream filter
> "*h264_mp4toannexb*" and everything worked.

Which decoder are you using?
There should be no bitstream filter needed for FFmpeg decoder afair.

Carl Eugen
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Re: [Libav-user] Demuxer not giving proper data to decoder ?

[ssshukla26]

After debugging, I realized that my decoder is getting data in *AVCC* format,
so on application side I added bit stream filter "*h264_mp4toannexb*" and
everything worked. No artefacts at all.

So to make sure that my decoder use data in *AnnexB* format, I added
*h264_mp4toannexb* filter *inside* decoder, filtering the incoming packet
data, so I don't have to change anything on application side. But I am
getting the below error.


"*Packet header is not contained in global extradata, corrupted stream or
invalid MP4/AVCC bitstream*"

Please help.






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