Audio stutters after pause/unpause

I'm on Windows 10 on the latest 4.0.0 Nightly build, i've tried with both avi and mkv files. It does not seem to happen to audio files (mp3, flac). Whenever after i pause the video and resume it, the audio stutters and it sounds like there's static. It doesn't happen if i quickly pause/unpause, only if i pause more than whatever X amount of time (like a few 100 ms). The audio fixes itself again if i click the timeline or use keyboard shortcuts to skip forwards/backwards in the movie. I recorded a video to show what happens: https://www.youtube.com/watch?v=gk2v4EKhBW4

assigned to @jbk

Please share logs.

added Component::Audio: Windows plugins label

changed milestone to %Bugs paradize

I don't know how to get the logs, i will upload them here if you can tell me how to get them =)

Added attachment:

• vlc-log.txt

Nvm, i think i managed to create the proper log-file and i've attached it here

Can you do the same with verbosity set to 2?

It doesn't have digits as options. But some googling tells me 2 is debug, so i'll provide a new file with verbosity set to debug.

Um i upgraded to "vlc-4.0.0-20180103-0504-dev-win64.exe" And it stopped happening, it doesn't even glitch out anymore even if i go back to "vlc-4.0.0-20180101-0506-dev-win64.exe" or "vlc-4.0.0-20180102-0506-dev-win64.exe" which are the 2 versions it happened on. So i can't get a debug file on the glitch now cause it won't happen anymore

Ok, now it's happening again all of a sudden, i'll attach the log file.

Added attachment:

• vlc-log.2.txt

Can you unplug your headphones, pelase?

New discovery: The glitch only seem to happen if i open VLC while the headphones are plugged in to the port in the front of the computer. But when i unplug the headphones it keeps happening on the speakers plugged into the back of the computer as well. If i open VLC with only the speakers plugged in to the back of the computer it doesn't happen. But on VLC Nightly 3.0.0 and 4.0.0 i can't switch from speakers to headphones without reopening VLC. On VLC 2.2.X i can plugin headphones while VLC is open and it'll switch automatically from speakers to headphones.

You can switch with the audio menu

Oh yea, they show up there now. Earlier in whatever Nightly 3.0.0 build i was using my headphones wouldn't show up in the list, so i had to restart VLC to change. But how come it doesn't just change automatically?

So the glitch starts happening as soon as any video starts playing while audio output is set to the computers front panel apparently, and then continues even on other outputs until i restart VLC. Can you reproduce it on your own? Or do you need me to get you some more logs? If so, could you tell me what you want me to do while logging? Like plug in/out headphones, stop/start playing a file, change audio output and whatnot.

I noticed this as well, when using the headphone and playing audio with more than 2 channels. So I suspected spatialaudio.cpp again.

After some tries, and comparing with other audio filters, removing p_sys->i_inputPTS seems to solve this problem:

diff --git a/modules/audio_filter/channel_mixer/spatialaudio.cpp b/modules/audio_filter/channel_mixer/spatialaudio.cpp
index d80e24a3ce..a217947882 100644
--- a/modules/audio_filter/channel_mixer/spatialaudio.cpp
+++ b/modules/audio_filter/channel_mixer/spatialaudio.cpp
@@ -85,7 +85,6 @@ struct filter_sys_t
 {
     filter_sys_t()
         : speakers(NULL)
-        , i_inputPTS(0)
         , inBuf(NULL)
         , outBuf(NULL)
     {}
@@ -119,7 +118,6 @@ struct filter_sys_t
     CAmbisonicSpeaker *speakers;
 
     std::vector<float> inputSamples;
-    mtime_t i_inputPTS;
     unsigned i_order;
 
     float** inBuf;
@@ -180,11 +178,8 @@ static block_t *Mix( filter_t *p_filter, block_t *p_buf )
     }
 
     p_out_buf->i_nb_samples = i_nbBlocks * AMB_BLOCK_TIME_LEN;
-    if (p_sys->i_inputPTS == 0)
-        p_out_buf->i_pts = p_buf->i_pts;
-    else
-        p_out_buf->i_pts = p_sys->i_inputPTS;
-    p_out_buf->i_dts = p_out_buf->i_pts;
+    p_out_buf->i_dts = p_buf->i_dts;
+    p_out_buf->i_pts = p_buf->i_pts;
     p_out_buf->i_length = p_out_buf->i_nb_samples * CLOCK_FREQ / p_filter->fmt_in.audio.i_rate;
 
     float *p_dest = (float *)p_out_buf->p_buffer;
@@ -246,8 +241,6 @@ static block_t *Mix( filter_t *p_filter, block_t *p_buf )
 
     assert(p_sys->inputSamples.size() < i_inputBlockSize);
 
-    p_sys->i_inputPTS = p_out_buf->i_pts + p_out_buf->i_length;
-
     block_Release(p_buf);
     return p_out_buf;
 }
@@ -256,7 +249,6 @@ static void Flush( filter_t *p_filter )
 {
     filter_sys_t *p_sys = p_filter->p_sys;
     p_sys->inputSamples.clear();
-    p_sys->i_inputPTS = 0;
 }
 
 static void ChangeViewpoint( filter_t *p_filter, const vlc_viewpoint_t *p_vp)

Since Flush() is never called when pause/unpause, it always remembers the pts from the previous sample and goes from there.

Does anyone know why it was done like this?

No, but we can ask around :)

You're just removing the interpolation. That will break any block without timestamp

I thought that this may break things, that's why I didn't submit any patch.

How does that work for the other filters?

to my understanding, it seems in your case the pts is saved before pause then reused when unpausing, and work with different pts. You need to trace timestamps to understand what goes wrong.

But isn't pts some kind of absolute time value, at least that's what it looks like to me. And in this case continuing to use the value from before the pause doesn't make sense to me.

I'm not sure if you're aware, but this bug is in 3.0 as well.

I can CONFIRM same Bluetooth issue here.

• Lenovo Yoga 2 Pro (20266)
• Windows 10 (1709) 64 bits
• VLC 3.0.0 (32 bits or 64 bits)

changed milestone to %3.0.x maintenance

fixed by 1f246d2604822174812a2cab63111d95ad6ea27a

added Status::fixed label

closed

changed milestone to %3.0.2

So... I'm experiencing the same issue with sound stuttering, but I don't understand the fix. Could somebody please explain what to do to fix this problem?

Wait for the next release or test a nightly build here https://nightlies.videolan.org/build/win64/vlc-3.0.2-20180312-0542/

mentioned in issue #19760 (closed)

mentioned in issue #19898 (closed)

I attach log of audio (of a video) stuttering after pause and/or move forward - move backward vlc 3.0.12 Pulseaudio 14.0 alsa-plugins-pulseaudio 1.2.2 phonon-qt5-backend-gstreamer 4.10.0 Fedora 33

vlc_log.txt

mentioned in issue #20549 (closed)

marked this issue as related to #20549 (closed)