Discussion:
[FFmpeg-user] Select a single program from mpegts
Robert Szelepcsényi
2018-11-13 08:38:31 UTC
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Hi,

I need an utility that can receive a complete mpeg transport stream on one
multicast address, select one particular program and stream it to another
multicast address. For example, this works perfectly for me:

ffmpeg -copy_unknown -i udp:/224.0.0.1:20001 -map 0:p:3001 -c copy -f
mpegts udp://224.0.0.2:20001

Program #3001 is a standard SD channel with MPEG2 video and MP2 audio.

However, when I try to stream program #3003, which is a HD channel with H264
video, I get the following error:

[mpegts @ 0x55dda31d41a0] dimensions not set
Could not write header for output file #0 (incorrect codec parameters ?):
Invalid argument

Metadata information for program #3001 is:

Program 3001
Metadata:
service_name : Jednotka
service_provider: Towercom
Stream #0:14[0xc1e]: Video: mpeg2video (Main) ([2][0][0][0] / 0x0002),
yuv420p(tv, top first), 720x576 [SAR 64:45 DAR 16:9], 25 fps, 25 tbr, 90k
tbn, 50 tbc
Stream #0:15[0xc27](slo): Audio: mp2 ([3][0][0][0] / 0x0003), 48000 Hz,
stereo, s16p, 192 kb/s
Stream #0:16[0xc28](qaa): Audio: mp2 ([3][0][0][0] / 0x0003), 48000 Hz,
stereo, s16p, 192 kb/s
Stream #0:17[0xc29](slo): Audio: mp2 ([3][0][0][0] / 0x0003), 48000 Hz,
mono, s16p, 64 kb/s (visual impaired)
Stream #0:0[0xc3a](slo): Subtitle: dvb_teletext ([6][0][0][0] / 0x0006)
Stream #0:1[0xc3b]: Data: bin_data ([6][0][0][0] / 0x0006)

and metadata information for program #3003 is:

Program 3003
Metadata:
service_name : Jednotka HD
service_provider: Towercom
Stream #0:0[0xc3a](slo): Subtitle: dvb_teletext ([6][0][0][0] / 0x0006)
Stream #0:1[0xc3b]: Data: bin_data ([6][0][0][0] / 0x0006)
Stream #0:2[0xce6]: Video: h264 (High) ([27][0][0][0] / 0x001B),
none(top first), 25 fps, 25 tbr, 90k tbn, 90k tbc
Stream #0:3[0xcef](slo): Audio: mp2 ([3][0][0][0] / 0x0003), 48000 Hz,
stereo, s16p, 192 kb/s
Stream #0:4[0xcf0](qaa): Audio: mp2 ([3][0][0][0] / 0x0003), 48000 Hz,
stereo, s16p, 192 kb/s
Stream #0:5[0xcf2](slo): Audio: mp2 ([3][0][0][0] / 0x0003), 48000 Hz,
mono, s16p, 64 kb/s (visual impaired)
Stream #0:6[0xd04]: Unknown: none ([5][0][0][0] / 0x0005)

It obviously lacks information about the picture size.

Increasing -probesize and -analyzeduration won’t help, but in fact, this is
not what I wish to do. I want ffmpeg just extract a given program and
generate a new mpegts without touching the contents. There is no problem
with completely unknown streams. I want the video and auto streams to be
handled in the same way. The end device can play the program, so there is
no point in trying to add information about picture size, which for some
reason cannot be successfully extracted.

In other words I need something like the famed getstream, which was just
demultiplexer/remultiplexer and nothing else without any deeper analysis of
the streams' content.

Is there any switch to force all streams being handled as unknown?


Robert


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Carl Eugen Hoyos
2018-11-27 18:48:59 UTC
Permalink
Post by Robert Szelepcsényi
I need an utility that can receive a complete mpeg transport stream on one
multicast address, select one particular program and stream it to another
ffmpeg -copy_unknown -i udp:/224.0.0.1:20001 -map 0:p:3001 -c copy -f
mpegts udp://224.0.0.2:20001
(I am not convinced that ffmpeg is the right tool for this kind of
retransmission, just in case this isn't obvious: A new output stream
is created with new properties, FFmpeg is unable to just strip the
unwanted parts of an mpeg stream.)
Post by Robert Szelepcsényi
Program #3001 is a standard SD channel with MPEG2 video and MP2 audio.
However, when I try to stream program #3003, which is a HD channel with H264
Command line and complete, uncut console output missing.

Carl Eugen
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