[FFmpeg-user] HTTP playlist stream copy to an IP QAM modulator

Anacelia Sarlo anacelia.sarlo at gmail.com
Wed Jul 20 15:38:06 EEST 2016


Reuben, thanks to answer. I did 2 tests :
1. I received the stream with VLC and I have a similar problem like with
the IP QAM.
2. Transcode the stream and the video its ok.

But my doubt is, if I receive the "stream copy" with ffplay, it runs
perfect!, so
it seems the response to my problem is, the way ffplay process/recover the
time base.

If I enable a debug it looks like every time ffmpeg make an http request
for
the playlist, there is a delay until receive it, and seems at this point
the video freeze, and then continue.
Thanks for another suggestion.
Ana

On Wed, Jul 20, 2016 at 12:56 AM, Reuben Martin <reuben.m at gmail.com> wrote:

> On Tuesday, July 19, 2016 10:16:03 PM CDT Anacelia Sarlo wrote:
> > ffmpeg -re -y -i $stream  -c copy -f mpegts -map 0:0 -map 0:1
> > -mpegts_pmt_start_pid 66 -streamid 1:71 -streamid 0:70 udp://
> > 192.168.1.108:1234?pkt_size=1316
> >
> > When I watch the stream from the cable network,  the audio is OK but the
> > video looks sometimes faltering and other times too fast, and out of
> sync.
> > But when I received this same output with ffplay it runs OK.
> > It seems there is a problem with the time base, I did many testings with
> > (genpts, copyts, etc)  with no good results.
>
> You might try and see what happens if you re-encode it rather than copying
> the
> media streams. Thing is with copying the stream you pass on any flaws that
> might be able to be corrected by ffmpeg, but are not as gracefully dealt
> with
> by other implementations.
>
> At least that might help narrow the problem down a bit and determine if the
> problem is with the origional source, or with ffmpeg.
>
> It would be nice to have a bit-stream filter to re-write time stamps when
> doing a stream copy, but sadly no such filter exists yet.
>
> -Reuben
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