sound.bdmv

Type of format	Audio Clip file
First released	2006
Developer	Blu-ray Disc Association
Max File Size	2 MB
Limits	128 sounds
Compression Type	CBR
Channels	2
Bits	16
Sample	48 KHz
Filename extension	sound.bdmv xxxxx.bdmv xxxx.pcm xxxx.lpcm
Open Format?	Yes
Free Format?	?
Magic Number	BCLK0100 BCLK0200 (BD) BCLK0300 (UHD)

Interactive Audio is used for real-time interactive sound effects, usually for menus or video games.

The sound.bdmv file (or other BDMV audio assets) is preloaded into the player's sound memory buffer before the Primary Video and Audio. It is restricted to PCM (stereo or mono) in 16 bit resolution at 48 kHz. The max size for each sound file (or group of sounds in the same file) is 2 MB. Audio length is 20 seconds in mono and 10 seconds in stereo. Sounds are loaded into the 8 MB sound memory, making it hold 80 seconds of mono audio and 40 seconds of stereo audio.

It can hold up to 128 sounds as long as it fits in the 2 MB sound.bdmv file. It is capable of playing multiple sound effects simultaneously. The exact number of simultaneous sounds that a sound.bdmv file can play is not explicitly specified in the Blu-ray Disc specification. So, there isn't a strict official limit. However, practical recommendations typically suggest keeping the number of simultaneous sounds manageable to ensure optimal performance across a range of Blu-ray players. A recommendation is to limit simultaneous sounds to around 16. This guideline helps ensure that audio playback remains smooth and that the interactive experience is not hindered by potential performance issues.

Some players, such as the Sony PlayStation 4 and the one's from Oppo, block Interactive Audio by default by automatically disabling the sound.bdmv file in the AUXDATA directory. So, to avoid this, its a good idea to store your sound files outside of the AUXDATA folder if you're making a BD-J application, such as a video game with cool sound effects.

Unclear Information

There are different sources regarding sound memory: Libbluray claims it is 8 MB, and Sony DoStudio claims it is 4 MB. Scenarist claims a single sound.bdmv file can not be greater than 2MB. Most BD titles that have used this file are always under 2 MB. However, the Pinball mini-game from Surf's Up contains 4.4 MB of compliant sound files (lpcm). So, it is unclear what the max sound memory is officially. Any legit information is appreciated!

Sources

• Cloudy with a Chance of Meatballs - Mini-game can play 4-5 sound effects in the same time (not counting primary audio)
• Tested the BD-J game, Ukko's Journey, sounds effects during gameplay
  
• Programming HD-DVD and Blu-ray Disc: The HD Cookbook
• Blu-play.com 
• Blu-disc Studio User's Guide 
• libbluray.java from VideoLAN
  

Author(s) : Æ Firestone