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FS#8670 - bugfix for overflow in mpc decoder (glitches)

Attached to Project: Rockbox
Opened by Andree Buschmann (Buschel) - Saturday, 01 March 2008, 18:01 GMT+2
Last edited by MichaelGiacomelli (saratoga) - Saturday, 08 March 2008, 22:26 GMT+2
Task Type Patches
Category Codecs
Status Closed
Assigned To No-one
Player Type All players
Severity Low
Priority Normal
Reported Version Daily build (which?)
Due in Version Undecided
Due Date Undecided
Percent Complete 100%
Private No

Details

Here is a patch for possibles glitches with mpc-playback. The was caused through internal overflow in the snythesis filter. This patch re-inserts a pre-/postscaling like it was implemented before the performance optimizations.
   mpc_overflow_v01.patch (4.7 KiB) 
 apps/codecs/libmusepack/synth_filter.c |   67 +++++++++++++++++----------------
 1 file changed, 35 insertions(+), 32 deletions(-)

This task depends upon

Closed by  MichaelGiacomelli (saratoga)
Saturday, 08 March 2008, 22:26 GMT+2
Reason for closing:  Accepted
Comment by Andree Buschmann (Buschel) - Sunday, 02 March 2008, 13:26 GMT+2
Update to have better "native" support for the optimizations which were made 6 months ago. Also this should still work for upocming float-versions.
Comment by Andree Buschmann (Buschel) - Sunday, 02 March 2008, 13:26 GMT+2
Now with patch.
   mpc_overflow_v02.patch (6.6 KiB) 
 apps/codecs/libmusepack/synth_filter.c |   82 +++++++++++++++++++--------------
 1 file changed, 49 insertions(+), 33 deletions(-)

Comment by MichaelGiacomelli (saratoga) - Tuesday, 04 March 2008, 19:18 GMT+2
Want me to commit this now or do you want to look at it more first?

Also, have you looked at SV8 support? I'm wondering how difficult it would be to support.
Comment by Andree Buschmann (Buschel) - Tuesday, 04 March 2008, 19:30 GMT+2
As this fix doesn't harm anything -> please commit :o)

Regarding the sv8-support: I did not check the sv8-sources, yet. So I can't estimate the effort... I assume the synthesis is untouched, but the bitstream decoder and requantization heavily changed. I guess large parts will need to be ported to fixed point again...
Comment by Thom Johansen (preglow) - Tuesday, 04 March 2008, 20:23 GMT+2
The SV7 sources were already fixed point, although not tested as much as floating point. I expect the SV8 lib status to be the same. Have you tried reporting this overflow stuff to the (current) musepack devs? I'd commit this right now, but don't have a development environment handy at the moment.

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