Author Topic: For Some Media Files Audio is Played over SPDIF, others Analog  (Read 660 times)

alx9r

  • Guru
  • ****
  • Posts: 187
    • View Profile
Here is what I am seeing:

For the vast majority of video files and (I think) all audio files in my collection sound is played through the coax SPDIF output.  However, for a few video files (perhaps 1 in 100) the audio is played on the analog output only.

Fortunately, both receivers i have used detect the audio source and switch inputs accordingly.  The main problem is that the analog audio is *much* quieter (>24dB) than that over SPDIF.

Has anyone else experienced this?


Here are some technical details:

Sound Hardware (According to alsamixer)
Card: HDA NVidia
Chip: Analog Devices AD1986A

I was able to extract some details from one of the files using VideoInspector.  The other file I had handy was not supported by Video Inspector.  Here is the output from the first one:
Code: [Select]
File Size : 2.23 Gb.

[Movie]
Valid : Yes [Matroska]
Duration : 00:11:00
Movie complete : Yes

[Video]
Resolution : 1080x1040
Codec : MPEG4 ISO advanced
FPS : 25.00
BitRate : 0 Kbps
Quality Factor : 0.00 b/px

[Audio]
Codec : AAC HE
Number of channels : 6
Sample Rate : 48000 Hz
BitRate : 0 Kbps

« Last Edit: March 29, 2009, 03:55:22 am by alx9r »

colinjones

  • Alumni
  • LinuxMCE God
  • *
  • Posts: 3003
    • View Profile
Re: For Some Media Files Audio is Played over SPDIF, others Analog
« Reply #1 on: March 28, 2009, 11:02:20 pm »
Maybe your audio chip doesn't support pass-thru for that audio codec? Is it a different codec than video files that do work?

alx9r

  • Guru
  • ****
  • Posts: 187
    • View Profile
Re: For Some Media Files Audio is Played over SPDIF, others Analog
« Reply #2 on: March 29, 2009, 03:46:20 am »
Maybe your audio chip doesn't support pass-thru for that audio codec?
I thought that any codec-related processing took place at a much higher level in software and that the audio data passed to the actual audio hardware was rather raw.

Is it a different codec than video files that do work?
These same thought has crossed my mind.  I am currently looking for a tool that will allow me to inspect the encoding of my media files en masse.

alx9r

  • Guru
  • ****
  • Posts: 187
    • View Profile
Re: For Some Media Files Audio is Played over SPDIF, others Analog
« Reply #3 on: March 29, 2009, 03:54:55 am »
Is it a different codec than video files that do work?
I just found a different file with the same audio encoding (AAC HE) that plays over SPDIF. 

Here are the details from the file:

Code: [Select]
File Size : 1.37 Gb.

[Movie]
Valid : Yes [Matroska]
Duration : 00:56:31
Movie complete : Yes

[Video]
Resolution : 720x400
Codec : MPEG4 ISO advanced
FPS : 25.00
BitRate : 0 Kbps
Quality Factor : 0.00 b/px

[Audio]
Codec : AAC HE
Number of channels : 2
Sample Rate : 24000 Hz
BitRate : 0 Kbps
« Last Edit: March 29, 2009, 03:57:45 am by alx9r »