Dumped opus streams have incorrect "Durations"., [TOS #6: moved from Scientific Discussion] Options

[bat_guano]

Hi
I've tried dumping some opus streams to file, but the results are strange.
Dumped files have incorrect "Durations".
This makes confusion when the files are played with VLC or SMPlayer etc.

What causes opus streams to create files with incorrect "Durations"?
And how can I fix it?

For example, a 30 second sample:-

CODE

timeout 30 ffmpeg -y -i http://radioserver1.delfa.net/64.opus -c copy SmoothJazz1.opus

MediaInfo shows incorrect Duration 4mn 17s.

General
Complete name : SmoothJazz1.opus
Format : OGG
File size : 258 KiB
Duration : 4mn 17s
Overall bit rate : 8 227 bps
Writing application : Lavf54.61.102

Audio
ID : 36710742 (0x2302956)
Format : Opus
Duration : 4mn 17s
Channel(s) : 2 channels
Channel positions : Front: L R
Sampling rate : 44.1 KHz
Compression mode : Lossy
Writing library : Lavf54.61.102

Similar results using MPlayer

CODE

rm -f fifo && mkfifo fifo; \
timeout 30 \
mplayer -nocache -noconsolecontrols -dumpstream -dumpfile fifo \
"http://radioserver1.delfa.net/64.opus" -demuxer lavf \
& ffmpeg -y -i fifo -c copy SmoothJazz2.opus \
&& rm -f fifo

MediaInfo shows incorrect Duration 2mn 18s.

General
Complete name : SmoothJazz2.opus
Format : OGG
File size : 254 KiB
Duration : 2mn 18s
Overall bit rate : 15.0 Kbps
Writing application : Lavf54.61.102

Audio
ID : 2098600889 (0x7D161BB9)
Format : Opus
Duration : 2mn 18s
Channel(s) : 2 channels
Channel positions : Front: L R
Sampling rate : 44.1 KHz
Compression mode : Lossy
Writing library : Lavf54.61.102

This post has been edited by bat_guano: Jan 24 2013, 23:32

[2012]

1st of all, those are Ogg-encapsulated Opus files.

Generally speaking, life streams are implemented in a way that clients can connect at arbitrary offsets.

In this case, the duration you see is correct! It's just the stream does not start from 0!

You can see that instantly if you play the saved file in mplayer, or if you run opusinfo:

CODE

WARNING: sequence number gap in stream 1. Got page 257 when expecting page 2. Indicates missing data. (normal for live streams)
WARNING: discontinuity in stream (1)
WARNING: EOS not set on stream 1 (normal for live streams)

[NullC]

In this case, the duration you see is correct! It's just the stream does not start from 0!

I don't think thats correct— unless there is some special mplayer convention it should be reporting the real duration of the provided file. There is no requirement that the times start at zero in a stream— I could, if I wanted, make opusenc choose random start times and I wouldn't expect it to break anything.