- Status Closed
- Percent Complete
- Task Type Patches
- Category Codecs
- Assigned To No-one
- Operating System All players
- Severity Low
- Priority Very Low
- Reported Version Release 3.9
- Due in Version Undecided
-
Due Date
Undecided
- Votes
- Private
FS#12443 - Multichannel downmix for flac
The attached patch implements multichannel-to-stereo downmixing for flac. For this all channels need to be decoded and saved in a dedicated sample buffer. For each channel configuration (3.0, 4.0, 5.0, 5.1) there is a matrix for the downmixing defined and applied.
The following file very clearly proves and shows the effect of the downmixing: http://download.linnrecords.com/test/flac/surround88.aspx
Closed by Buschel
2011-12-14 19:18
Reason for closing: Accepted
Additional comments about closing: Warning: Undefined array key "typography" in /home/rockbox/flyspray/plugins/dokuwiki/inc/parserutils.php on line 371 Warning: Undefined array key "camelcase" in /home/rockbox/flyspray/plugins/dokuwiki/inc/parserutils.php on line 407
2011-12-14 19:18
Reason for closing: Accepted
Additional comments about closing: Warning: Undefined array key "typography" in /home/rockbox/flyspray/plugins/dokuwiki/inc/parserutils.php on line 371 Warning: Undefined array key "camelcase" in /home/rockbox/flyspray/plugins/dokuwiki/inc/parserutils.php on line 407
Submitted with r31253
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Next version:
- Moved donwmix to an own function
- Moved scaling into downmixing to improve performance
- Avoid divisisions to improve performance
A sample file (5.1, 88.2 kHz, 24 bit) on iPod Video needs:
svn → 96.8 MHz (no downmix, left/right only)
v02 → 101.9 MHz (5.1-downmix)
Now with manual changes as well.
ToDo's (maybe after the patch is in): A little more tweaking with IRAM allows a speed up of ~3 MHz on PP5022.
this is working on my device. (fuze+)
tested: patch v04 on both test file and a regular song, stereo flac still plays
FWIW if you're concerned about speed, the rounding probably isn't needed for 32 bit samples.
You are talking about sections like "(b + (b«2))»5"? This is equal to b*(1+4)/32 = b*5/32 ~= 1/6, but avoids multiplication or division.