[Libav-user] HLS: Exactly constant segment duration

[Andrey Mochenov]

Hi,

Thank you for your answer.
I suppose, IDR stands for Instantaneous Decoding Refresh.
 Please, explain: what do you mean under "set encoder with all idr"?
What settings I need to use?

Andrey.

On Mon, Aug 19, 2013 at 10:48 AM, Anshul maheshwari <
er.anshul.maheshwari at gmail.com> wrote:

>   Please dont top post over here
>
> Try to set encoder with all idr,  that may give you const duration
>
  On Aug 15, 2013 4:59 PM, "Andrey Mochenov" <andrey2067 at gmail.com> wrote:
> >
> > Hi,
> >
> > We are using FFmpeg libraries git-ee94362 libavformat v55.2.100.
> > Our purpose is to mux two streams (video and audio) into M3U8 playlist
> using HLS.
> > In addition, we want the duration of every TS segment file be exactly
> 3.0 sec (frame rate is 25 fps).
> > To reach it, we are trying to set several options and properties,
> namely:
> > - segment_time
> > - keyint_min
> > - scenechange_threshold
> > - gop_size
> > - force_key_frames.
> >
> > And our code looks as below:
> >
> > AVCodecContext *codec_ctx = NULL;
> > AVFormatContext *ofmt_ctx = NULL;
> > int ret = 0, gopSize = (int)(3.0 * 25);   // 3 sec * 25 fps
> >
> > // ofmt_ctx and codec_ctx initialization and filling are OK, but:
> >
> > codec_ctx->time_base.num = 1;
> > codec_ctx->time_base.den = 25 // fps
> >
> > // It seems, that the following three lines have no effect without
> explisit setting of the "hls_time" property
> > codec_ctx->keyint_min = gopSize;       // in FFMpeg application, the
> corresponding option is "-keyint_min 3"
> > codec_ctx->scenechange_threshold = 0;  // in FFMpeg application, the
> corresponding option is "-sc_threshold 0"
> > codec_ctx->gop_size = gopSize;         // in FFMpeg application, the
> corresponding option is "-g 3"
> >
> > ret = av_opt_set_double(ofmt_ctx, "hls_time", 3.0,
> AV_OPT_SEARCH_CHILDREN);
> >
> > // Any of the following lines causes "Option not found" error.
> > ret = av_opt_set(codec_ctx->priv_data, "profile", "main",
> AV_OPT_SEARCH_CHILDREN);
> > ret = av_opt_set(codec_ctx->priv_data, "preset", "ultrafast",
> AV_OPT_SEARCH_CHILDREN);
> > ret = av_opt_get(ofmt_ctx, "segment_time",  AV_OPT_SEARCH_CHILDREN,
> &str);
> > ret = av_opt_set((ofmt_ctx, "segment_time", "3.0",
> AV_OPT_SEARCH_CHILDREN);
> >
> > Anyway, the TS files durations are different, (~2-3 sec), and not
> EXACTLY 3.0 sec.
> > Our question: What is the best way to solve the problem?
> >
> > Andrey Mochenov.
> >
> >
> > _______________________________________________
> > Libav-user mailing list
> > Libav-user at ffmpeg.org
> > http://ffmpeg.org/mailman/listinfo/libav-user
> >
>
> Please dont top post over here
>
> Try to set encoder with all idr,  that may give you const duration
>
> _______________________________________________
> Libav-user mailing list
> Libav-user at ffmpeg.org
> http://ffmpeg.org/mailman/listinfo/libav-user
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://ffmpeg.org/pipermail/libav-user/attachments/20130819/dfcb5d81/attachment.html>