[Libav-user] Decoding single NALUs from x264 programmatically (no luck even with parser), works fine with concatenated NALUs

[Faraz Khan]

So I got the decoder to work with the parser! It was a bug on my end -
However it still seems that the parser waits for the entire frame to
complete and then sets an outsize? Is this intentional? Is it possible to
decode a single NALU?



On Mon, Jun 10, 2013 at 2:57 PM, Faraz Khan <faraz at screenhero.com> wrote:

> So the keyframe cannot be fed to the decoder one nal at a time? Is that
> what you are suggesting?
>
>
>
>
> On Mon, Jun 10, 2013 at 2:40 PM, Andy Shaules <bowljoman at gmail.com> wrote:
>
>>  I always had to decode from the latest key frame up to the desired
>> stream time nal,
>>
>>
>> On 6/10/2013 2:36 PM, Faraz Khan wrote:
>>
>> Hi all,
>> I'm trying to use ffmpeg as a decoder for a real-time x264 stream that
>> I'm generating. It works fine if I try to decode entire frames, but if I
>> try to decode a single NALU the decoder errors out saying 'no frame'. I've
>> tried using the parser (av_parser_parse2) but the h264 decoder doesnt seem
>> to like that output either. I'm using x264 with annex-b and repeat-headers
>> on.
>>
>>  The encoder config is as follows:
>>
>> x264params.b_sliced_threads = 1;
>> x264params.i_slice_max_size = 1350;
>> x264params.i_width = yuvSize.width;
>> x264params.i_height = yuvSize.height;
>> x264params.i_fps_num = 10;
>> x264params.i_fps_den = 1;
>> x264params.b_vfr_input = 0;
>> x264params.rc.i_bitrate = 1500;
>>
>>   // Intra refres:
>> x264params.i_keyint_max = 50000000;
>> x264params.b_intra_refresh = 1;
>>
>>  //Rate control:
>>
>> x264params.rc.i_rc_method = X264_RC_ABR;
>> x264params.rc.i_vbv_buffer_size = 300;
>> x264params.rc.i_vbv_max_bitrate = 1500;
>>
>>  //For streaming:
>> x264params.b_repeat_headers = 1;
>> x264params.b_annexb = 1;
>>
>>  x264_param_apply_profile(&x264params, "baseline");
>>
>>
>>
>>  I do the encode with:
>>
>>     int frame_size = x264_encoder_encode(x264Encoder, &nals, &i_nals, &
>> pic_in, &pic_out);
>>
>>
>>  Now, since the max slice size is 1350, each packet output is a udp
>> packet of size < MTU (this is true) and sent across the network.
>>
>> I iterate over the nals[i].p_payload and send them over to the ffmpeg
>> side for decoding. I receive the correct packet on the remote side.
>>
>> If I assemble ALL the NALUs that were output in this frame and feed it
>> directly to the decoder (even without the parser), it works fine! If I feed
>> one NALU at a time, it fails (event with the parse). I'm sending it to the
>> parser like:
>>
>>
>>  int plen = av_parser_parse2(codecParser, decoderContext, &outbuf,
>> &outside, indata,inlength,0,0,0);
>>
>>
>>  plen always reports that it consumed the entire NALU that I gave it -
>> after consuming a few NALUs, the outsize and outbuf are set to some value.
>> Feeding it into the decoder using:
>>
>>
>>   int len = avcodec_decode_video2(decoderContext,decoderOutframe,
>> &gotpic,&avpkt);
>>
>>
>>  Results in it saying 'No frame'. Again, if avpkt.data contains the
>> entire frame (all NALUs concatenated) it will work!
>>
>>
>>  I'm obviously doing some obviously wrong - but I really cant figure out
>> why it wont decode a single NALU. Or is this a limitation in ffmpeg?
>>
>>
>>  Thanks Guys!
>>
>>
>>
>>
>> --
>> Faraz Khan
>> Simple Collaboration Screensharing
>> www.screenhero.com
>>
>>
>> _______________________________________________
>> Libav-user mailing listLibav-user at ffmpeg.orghttp://ffmpeg.org/mailman/listinfo/libav-user
>>
>>
>>
>> _______________________________________________
>> Libav-user mailing list
>> Libav-user at ffmpeg.org
>> http://ffmpeg.org/mailman/listinfo/libav-user
>>
>>
>
>
> --
>
> --
> Faraz Khan
> Simple Collaboration Screensharing
> www.screenhero.com
>



-- 

--
Faraz Khan
Simple Collaboration Screensharing
www.screenhero.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://ffmpeg.org/pipermail/libav-user/attachments/20130610/7efd087d/attachment.html>