[Libav-user] streaming raw H.264 to HLS

Evan Odabashian eodabash at gmail.com
Wed Oct 10 01:58:04 EEST 2018

It appears my problem was due to lack of IDR frames - playing the segments
with ffplay gave me some more error messages to google ;-) I was able to
get it working by forcing nvenc to emit an IDR frame at the beginning of
each GOP. I can't figure out if there's a way to tell from the parser
whether the current frame is an IDR frame or just a regular I frame though,
should this be possible to detect?

On Tue, Oct 9, 2018 at 10:30 AM Evan Odabashian <eodabash at gmail.com> wrote:

> Well that is basically what I'm doing already, using the built-in HLS
> muxer not manually creating the ts segments and playlist. I'm using the
> h264 parser because the samples I'm receiving from nvenc are not complete
> frames so I'm using the parser to assemble the full frames then give them
> to the muxer via av_interleaved_write_frame.
> Presumably the HLS muxer (which I believe is the code located in hlsenc.c
> right?) knows how to build valid HLS segments so I can only assume I'm
> misrepresenting something to it about the frames I'm providing.
> On Tue, Oct 9, 2018 at 4:42 AM He Lei <helei0908 at hotmail.com> wrote:
>> Many frames are keyframes. such as SPS/PPS and I frames, If you generate
>> the hls_list file yourself,  and mux as ts file.  It has to start with SPS
>> and PPS, and then I frame;
>> Another way, you can mux as hls, that would be easier():
>> avformat_alloc_output_context2(&format_ctx, xxx, “hls”, xxx);
>> and set the  hls_list_size to 0:
>> av_opt_set_int(format_ctx, “hls_list_size”, 0, 0);
>> If you want to format the list,also use av_opt_set.
>> This command tells you something you can set: “ffmpeg -h muxer=hls”
>> LeiHe
>> helei0908 at hotmail.com
>> 在 2018年10月9日,上午8:38,Evan Odabashian <eodabash at gmail.com> 写道:
>> I'm trying to use libavformat to write a stream of H.264 data (coming
>> from the NvCodec API) directly (without re-encoding) to an HLS playlist.
>> I'm sending the packets returned by the encoder through av_parser_parse2
>> until I get a complete frame, and then writing the resulting frame with
>> av_interleaved_write_frames. This is mostly working in that I get an m3u8
>> playlist + .ts segments that plays back successfully if it starts from the
>> first .ts segment (and can play through any number of subsequent segments).
>> I'm not able to start playback directly from any segment after the first
>> one however. Viewing the file details in Windows explorer for the first .ts
>> segment shows correct values for the frame dimensions, bitrate, and frame
>> rate. For all other segments however these values are wrong (and not
>> consistent from one file to the next). I'm pretty sure each new segment is
>> beginning on a keyframe (in that I see the new .ts file appear right after
>> the parser detects a keyframe and I write the output frame with
>> the AV_PKT_FLAG_KEY flag). I can change the segment duration to any value I
>> want (1 second, 10 seconds, etc) and see the same behavior I don't think
>> this is an issue with the incoming sample themselves.
>> Can anyone guess what might be the problem here, or have some ideas to
>> try and diagnose the problem further?
>> _______________________________________________
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>> Libav-user at ffmpeg.org
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