After reading around, it appeared to be different per device/application. Now I'm not a guru on the specifics of codecs but from playing with tools in the past and with new ones to examine this recent incident, there were some key points to note (oh, I didn't mention it yet but I'm using MPEG-4):
- There can exist multiple audio tracks for a single file.
- Each track has an identifier (number) assigned to it.
- An audio track can have (don't know if it's 'required') a language value assigned it.
- There is a flag (or something) which classifies the track as enabled or disabled.
The Test Plan
I prepared a total of eight (8) video files; four (4) files had 2CH track at a lower identifier than the 5.1CH track, the other vice versa. The groups of four (4) files had all cases of setting the 2CH track and 5.1CH track enabled and/or disabled. Now to see how the PlayStation reacts! I browsed the media on the PS3 and when opened, looked at the status bar to see what audio channel the system had chosen. The results are here:
|Test File||First Audio Track||2 Channel Audio Disabled||5.1 Channel Audio Disabled||PS3 Selection|
After looking at these results, this is the process I believe the PS3 will do:
- Use the first available audio track which matches the preferred language (a PS3 setting) that is enabled.
- If no track is found, use the first available audio track which matches the preferred language.
- If no track is found, use whatever I can get my hands on!
- For all future encodings, give a higher priority to the 5.1CH audio track.
- For all current encodings, disable the 2CH audio track and enable the 5.1CH audio track.
Now I no longer have to be bothered in checking if the video I am watching has 5.1 surround sound when I wish to play it.
Other who stumble onto this same problem might be curious to know how to enable/disable the audio tracks in an MPEG-4 file. I was using MP4Box to modify my already transcoded movie files. From my Handbrake preset, track two (2) was my 2CH audio track and track three (3) was my 5.1CH audio track (for movies that had 5.1 surround sound). I used the following command to disable track two (2) and enable track three (3):