mirror of https://bitbucket.org/ausocean/av.git
113 lines
3.5 KiB
Markdown
113 lines
3.5 KiB
Markdown
# Readme
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revid is a testbed for re-muxing and re-directing video streams as
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MPEG-TS over various protocols.
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# Description
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The mode (-m) determine the mode of operation:
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* h = send HTTP (as a POST)
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* u = send UDP
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* r = send RTP
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* f = write to /tmp files
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* d = inspect packets and dump to screen
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Flags (-f) determine video filtering and other actions.
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For example, to send as raw UDP to <PORT> on the current host, passing the video and audio as is:
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revid -i <RTSP_URL> -m u -o udp://0.0.0.0:<PORT>
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Or, to post as HTTP to <HTTP_URL>, fixing PTS and dropping the audio along the way:
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revid -i <RTSP_URL> -m h -f 3 -o <HTTP_URL>
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Note that revid appends the size of the video to the URL to supply a query param.
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Append a ? to your <URL> if you don't need it
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List of flags:
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* filterFixPTS = 0x0001
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* filterDropAudio = 0x0002
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* filterScale640 = 0x0004
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* filterScale320 = 0x0008
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* filterFixContinuity = 0x0010
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* dumpProgramInfo = 0x0100
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* dumpPacketStats = 0x0200
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* dumpPacketHeader = 0x0400
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* dumpPacketPayload = 0x0800
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Common flag combos:
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* 3: fix pts and drop audio
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* 7: fix pts, drop audo and scale 640
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* 17: fix pts and fix continuity
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* 256: dump program info
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* 512: dump packet stats
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* 513: fix pts, plus above
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* 529: fix pts and fix continuity, plus above
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# Errors
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If you see "Error reading from ffmpeg: EOF" that means ffmpeg has
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crashed for some reason, usually because of a bad parameter. Copy and
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paste the ffmpeg command line into a terminal to see what is
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happening.
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RTSP feeds from certain cameras (such as TechView ones) do not
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generate presentation timestamps (PTS), resulting in errors such as
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the following:
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* [mpegts @ 0xX] Timestamps are unset in a packet for stream 0...
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* [mpegts @ 0xX] first pts value must be set
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This can be fixed with an ffmpeg video filter (specified by flag 0x0001).
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Another issue is that MPEG-TS continuity counters may not be continuous.
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You can fix this with the fix continuity flag (0x0010).
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FFmpeg will also complain if doesn't have the necessary audio codec
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installed. If so, you can drop the audio (flag 0x0002).
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# MPEG-TS Notes
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MPEG2-TS stream clocks (PCR, PTS, and DTS) all have units of 1/90000
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second and header fields are read as big endian (like most protocols).
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* TEI = Transport Error Indicator
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* PUSI = Payload Unit Start Indicator
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* TP = Transport Priority
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* TCS = Transport Scrambling Control
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* AFC = Adapation Field Control
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* CC = Continuity Counter (incremented per PID wen payload present)
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* AFL = Adapation Field Length
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* PCR = Program Clock Reference
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# Dependencies
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revid uses ffmpeg for video remuxing.
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See [Ffmepg filters](https://ffmpeg.org/ffmpeg-filters.html).
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revid also uses [Comcast's gots package](https://github.com/Comcast/gots).
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# Author
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Alan Noble <anoble@gmail.com>
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# License
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revid is Copyright (C) 2017 Alan Noble.
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It is free software: you can redistribute it and/or modify them
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under the terms of the GNU General Public License as published by the
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Free Software Foundation, either version 3 of the License, or (at your
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option) any later version.
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It is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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or more details.
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You should have received a copy of the GNU General Public License
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along with revid in gpl.txt. If not, see [GNU licenses](http://www.gnu.org/licenses/).
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