[BUG] WebM with Opus audio no sound

[sakarie9]

WebM with opus

wf-recorder -f v.webm -c libvpx -a -C libopus

wf-recorder output

Setting codec option: cpu-used=5
Setting codec option: deadline=realtime
Using video filter: null
[libvpx @ 0x7d773c001c80] v1.14.1
[libvpx @ 0x7d773c001c80] Neither bitrate nor constrained quality specified, using default CRF of 32 and bitrate of 256kbit/sec
Setting codec option: cpu-used=5
Setting codec option: deadline=realtime
Choosing sample format s16 for audio codec libopus
[libopus @ 0x7d773c4ff1c0] No bit rate set. Defaulting to 96000 bps.
Output #0, webm, to 'v.webm':
  Stream #0:0: Video: vp8, yuv420p(pc), 1920x1080 [SAR 1:1 DAR 16:9], q=2-31, 256 kb/s
      Side data:
        cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: N/A
  Stream #0:1: Audio: opus, 48000 Hz, stereo, s16, 96 kb/s
Using PulseAudio device: default
[Source @ 0x7d773c004fc0] Changing video frame properties on the fly is not supported by all filters.
[Source @ 0x7d773c004fc0] filter context - w: 1920 h: 1080 fmt: 119 csp: gbr range: unknown, incoming frame - w: 1920 h: 1080 fmt: 119 csp: unknown range: unknown pts_time: 0.008543

mediainfo output

General
Complete name                            : v.webm
Format                                   : WebM
Format version                           : Version 4
File size                                : 251 KiB
Duration                                 : 3 s 468 ms
Overall bit rate                         : 592 kb/s
Writing application                      : Lavf61.7.100
Writing library                          : Lavf61.7.100

Video
ID                                       : 1
Format                                   : VP8
Codec ID                                 : V_VP8
Duration                                 : 3 s 234 ms
Width                                    : 1 920 pixels
Height                                   : 1 080 pixels
Display aspect ratio                     : 16:9
Frame rate mode                          : Variable
Compression mode                         : Lossy
Default                                  : No
Forced                                   : No
Color range                              : Full

Audio
ID                                       : 2
Format                                   : Opus
Codec ID                                 : A_OPUS
Duration                                 : 3 s 468 ms
Channel(s)                               : 2 channels
Channel layout                           : L R
Sampling rate                            : 48.0 kHz
Bit depth                                : 16 bits
Compression mode                         : Lossy
Delay relative to video                  : -12 ms
Default                                  : No
Forced                                   : No

The resulting .webm file plays video correctly but has no audio.

VP8, VP9 and AV1 with Opus have same problems.

WebM with Vorbis

wf-recorder -f v.webm -c libvpx -a -C libvorbis

Works perfectly. Both video and audio playback are fine.

MP4 with opus

wf-recorder -f v.mp4 -c hevc_vaapi -a -C libopus

Works perfectly. Both video and audio playback are fine.

Environment Details:

• wf-recorder 0.5.0
• sway 1.10

Additional

A potentially similar issue was found here.

[ThomasBaruzier]

Same issue here, did you find a solution? I'm sticking with h264 for now.

[soreau]

Apparently this option is problematic. It seems to work fine with -pdeadline=best or -pdeadline=good.

EDIT: I was mistakenly testing with libvorbis so, it's still broken, not matter the vpx options set.

[ThomasBaruzier]

I guess vp9 + vorbis is better than h264 + opus, so there's that

[soreau]

So I've found that this patch fixes the issue:

diff --git a/src/frame-writer.cpp b/src/frame-writer.cpp
index 5cdf2d0..24e2ae9 100644
--- a/src/frame-writer.cpp
+++ b/src/frame-writer.cpp
@@ -558,7 +558,7 @@ void FrameWriter::init_audio_stream()
     audioCodecCtx->channels = av_get_channel_layout_nb_channels(audioCodecCtx->channel_layout);
 #endif
     audioCodecCtx->sample_rate = params.sample_rate;
-    audioCodecCtx->time_base = (AVRational) { 1, 1000 };
+    audioCodecCtx->time_base = (AVRational) { 1, 0 };
 
     if (fmtCtx->oformat->flags & AVFMT_GLOBALHEADER)
         audioCodecCtx->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;

..but also causes libopus to spew a repeated message:

[libopus @ 0x7a681021cf40] Queue input is backward in time

[ThomasBaruzier]

@soreau I found a fix, but it would require more testing regarding other video/audio codecs combinations.