[FFmpeg-devel] [PATCH 0/3] Patch set to delay output live stream

[Tao Zhang]

Andreas Rheinhardt <andreas.rheinhardt at gmail.com> 于2020年4月30日周四 下午1:45写道：
>
> Tao Zhang:
> > Marton Balint <cus at passwd.hu> 于2020年4月30日周四 上午4:55写道：
> >>
> >>
> >>
> >> On Thu, 30 Apr 2020, Tao Zhang wrote:
> >>
> >>> Marton Balint <cus at passwd.hu> 于2020年4月30日周四 上午12:03写道：
> >>>>
> >>>>
> >>>>
> >>>> On Wed, 29 Apr 2020, leozhang wrote:
> >>>>
> >>>>> In some applications, it is required to add delay to live streaming.
> >>>>
> >>>> In what applications? And if you do this, why not run
> >>>>
> >>>> sleep 20; ffmpeg ....
> >>> In live streaming applications, someone wouldn't want broadcast what's
> >>> comming next immediately.
> >>> Sleep 20 then ffmpeg is not ok, because the stream is still
> >>> broadcasting immediately, and lost 20 seconds signal.
> >>
> >> So you want to buffer 20 seconds of input, and then start the output?
> > yes
> >>
> >>>>
> >>>> I don't see how this is useful at all.
> >>>>
> >>>> And what is -paced? What it is used for? Isn't it the same as using ffmpeg
> >>>> -re? You really should better explain your use case.
> >>> -re read the input, -paced write the output.
> >>
> >> But why do you want to delay every output packet?
> > By default, ffmpeg will output packets as fast as possible.
> > So I delay output every packet at native frame rate to simulate live stream.
>
> What would be the benefit of your patch for API users (i.e. users that
> directly use libavformat and not ffmpeg.c)? Right now your problem seems
> to be in ffmpeg.c and not in libavformat.
API users can use the fifo psedo muxer directly, without implementing
the similar functions by themself.
> >>
> >>>>
> >>>> Regards,
> >>>> Marton
> >>>>
> >>>>> For example, you can add 20 seconds to rtmp stream with below command:
> >>>>> ffmpeg -i your_input_stream_address -c copy -map 0:a -map 0:v -f fifo -paced 1 -queue_size 6000000
> >>>>> -output_delay 20000000 -fifo_format flv rtmp://example.com/live/delayed_stream_name
> >>>>>
> >>>>> leozhang (3):
> >>>>>  avformat/fifo: add option to delay output
> >>>>>  avformat/fifo: add option to write packets in paced way
> >>>>>  doc/muxers: add command example how to delay output live stream
> >>>>>
> >>>>> doc/muxers.texi    | 17 +++++++++++++++++
> >>>>> libavformat/fifo.c | 26 ++++++++++++++++++++++++++
> >>>>> 2 files changed, 43 insertions(+)
> >>>>>
> >>>>> --
> >>>>> 1.8.3.1
> >>>>>
>
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