Arch Linux

OrthoCube

Member

Registered: 2018-05-01

Posts: 1

Weird MP3-only Playback Issue + VLC Glitches

I have noticed that whenever I play MP3 audio, I get glitches (stereo squeaks/glitches/scratches) that disappears about 1 minute into the song. This behavior is shown on both MOC (which outputs audio via ALSA but PulseAudio catches it anyway) and VLC (which outputs to PulseAudio directly). I have mostly WavPack files so I didn't notice it sooner, but now that I know my configuration has a problem, I'm really bothered with it.

Of course, I did try the PulseAudio troubleshooting guide on the wiki, but none of the fixes helped me. I can imagine, since I think PulseAudio works acually fine (since it works as long as the file isn't an MP3. Haven't tried with Ogg Vorbis files (I don't have such files, I can encode some but I don't think if it'd really help, since even if Vorbis played well, MP3 still doesn't. I have tried playing WavPack and M4A (AAC) files, and both do not exhibit the problem.

However, I also have problems with VLC that might be related, because I often get glitched video at approx first 15 seconds of the video and the audio mutes at around 30 seconds in.

Here are the significant VLC log output parts:

main debug: looking for hw decoder module matching "any": 3 candidates
main debug: using hw decoder module "vaapi"
avcodec info: Using Intel i965 driver for Intel(R) Kaby Lake - 2.1.0 for hardware decoding
main debug: Received first picture
main debug: Decoder wait done in 227 ms
pulse debug: cannot synchronize start
pulse debug: deferring start (33013 us)
pulse debug: deferring start (9824 us)
pulse warning: starting late (-13721 us)
pulse debug: started
pulse debug: underflow
pulse debug: underflow
pulse debug: changing sink 0: alsa_output.pci-0000_00_1f.3.analog-stereo (Built-in Audio Analog Stereo)
pulse debug: underflow
main debug: picture might be displayed late (missing 5 ms)
main debug: auto hiding mouse cursor
main warning: picture is too late to be displayed (missing 38 ms)
main warning: picture is too late to be displayed (missing 43 ms)
main debug: picture might be displayed late (missing 1 ms)
main debug: resized to 928x424
main debug: VoutDisplayEvent 'resize' 928x424
faad warning: Maximum number of bitstream elements exceeded
faad warning: Maximum number of bitstream elements exceeded
faad warning: Maximum number of bitstream elements exceeded
faad warning: Unexpected channel configuration change
faad warning: decoded zero sample
main debug: inserting 6468 zeroes
mp4 warning: track[0x2] will be disabled (eof?): Failed to read -1315920219 bytes sample at 18505791
faad warning: Bitstream value not allowed by specification
main debug: killing decoder fourcc `mp4a'
main debug: removing module "faad"
main debug: removing module "samplerate"
main debug: removing module "scaletempo"
main debug: removing module "float_mixer"
main debug: keeping audio output
pulse debug: changing sink 0: alsa_output.pci-0000_00_1f.3.analog-stereo (Built-in Audio Analog Stereo)
main debug: VoutDisplayEvent 'mouse button' 0 t=6
main debug: VoutDisplayEvent 'mouse button' 0 t=7
main debug: toggling resume
main debug: auto hiding mouse cursor
main debug: auto hiding mouse cursor

Does someone have maybe encountered this before, or can give me clues as to why this is happening? My hardware is running on snd-hda-intel and I have proper working i965 drivers from the video (and it can be seen that VLC uses hardware video decoding). I think the problem lies within PulseAudio or the AAC decoder (since VLC thinks the audio stream is finished already even when it isn't yet). If you need more information, please tell me, I will provide the info you need as soon as I can.

Thank you very much!

Last edited by OrthoCube (2018-05-01 10:23:10)

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 25,232

Re: Weird MP3-only Playback Issue + VLC Glitches

Once pulseaudio has your audio it has already been decoded and isn't an MP3 anymore, might be a specific constellation with those specific files you are trying to use. Can you post

pacmd list-sinks
pacmd list-sink-inputs

during playback of a problematic file.  FWIW does direct hardware access also have the same issue? Try e.g. from a terminal

mpg123 -o pulse $pathtomp3 #Just to check if a different decoder has the same issue
mpg123 -a hw:0 $pathtomp3 #Will use direct hardware access

while nothing else is playing. Some more general info on your setup would be nice like what specific model of CPU and audio hardware we are dealing with.

As for VLC, try turning hardware acceleration off specifically it can have issues depending on the input file. And maybe even before that move the Video Output module from Automatic to OpenGL or similar.

Last edited by V1del (2018-05-02 09:00:13)