FS#11231 - Skipping and stuttering in low bitrate .WMA files

Attached to Project: Rockbox
Opened by Michael Bauminger (mikebomb) - Friday, 30 April 2010, 09:35 GMT
Task Type Bugs
Category Codecs
Status Unconfirmed
Assigned To No-one
Operating System Sansa e200
Severity Low
Priority Normal
Reported Version Release 3.4
Due in Version Undecided
Due Date Undecided
Percent Complete 0%
Votes 0
Private No


This is actually release 3.5.1

I have quite a few low bitrate .wma audio files that play fine in the original firmware, play fine in VLC, but skip, stutter, and hiss in Rockbox.

The file is 20kbps, 22 kHz, mono, Windows Media Audio V2.

I have attached a sample cut from a larger file. Like the original files, it plays fine in the original firmware and in VLC.
This task depends upon

Comment by MichaelGiacomelli (saratoga) - Saturday, 19 June 2010, 00:39 GMT
Confirmed that this is a bug. It looks like this file causes some kind of error in quantization because the difference between the fixed and floating point decoders is concentrated in low frequencies, with very little error in mids, and less in highs.
Comment by MichaelGiacomelli (saratoga) - Wednesday, 27 July 2011, 19:49 GMT
Played around with this some more. It seems that the hgain_vlc table is either not setup correctly, or not accessed correctly and encounters a number of invalid vlc codes. I tested 3.4 (before we reworked the ffmpeg code) and it also fails.
Comment by MichaelGiacomelli (saratoga) - Thursday, 28 July 2011, 14:15 GMT
r30220 fixes one of the bugs in this file. Still doesn't decode correctly yet :(
Comment by Michael Bauminger (mikebomb) - Thursday, 27 October 2011, 07:40 GMT
This bug is related to the codec, not necessarily the bit rate. I have converted some of the files I have from 20kbps, 22kHz, mono, Windows Media Audio V2 to the same bitrate and sampling in Windows Media Audio V9.2 using Switch Sound File Converter. The files in the 9.2 version of the codec play just fine in Rockbox, even thougn they are still 20kbps, 22kHz, mono Windows Media Audio.