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fre:ac development status update 04/2018 Print
Written by Robert   
Tuesday, 01 May 2018 12:28

It's time for a new development status update after an interesting month.

Optimized CRC routines for audio codecs

In case you missed it, here is my article on speeding up LAME, FLAC, Ogg and Monkey's Audio with faster CRC checks. The proposed CRC algorithm is roughly 5 times faster than the one previously used and results in a speedup of about 5% for FLAC encoding and decoding. Patches have been submitted to the upstream projects and I hope for integration in official releases of these codecs.

Fixed crashes with local CDDB queries

A user reported occasional crashes when querying a local CDDB database on Linux. This turned out to be a thread-safety issue that manifested itself only when the CDDB query dialog was displayed and then immediately closed before the main thread finished processing the window mapping event.

The issue affects all systems using the X11 window system, so it can happen on Linux, FreeBSD and other Unix-like systems.

This and another issue that I found while investigating it will be fixed in the next alpha release.

SuperFast LAME nearing completion

A whole bunch of changes have been incorporated into the SuperFast version of the LAME MP3 encoder component. It's almost complete now and an official preview release is getting closer.

This month's changes include:

  • Support for CBR mode and VBR rate limiting
  • Support for MP3s with frame CRCs
  • Writing Xing header table of contents
  • Writing Xing header CRCs

There is just one item left on my list now which is related to handling the bit reservoir in high complexity situations (especially with MPEG 2 streams at 22.05 or 24 kHz). In that case it can happen that an encoder thread tries to use more reservoir than actually is available. Special handling has to be implemented to resolve such situations. I hope to be able to finish this in May.

While waiting for SuperFast LAME, make sure to check out the 2nd SuperFast preview release with added support for FDK-AAC and Speex and tuning for Opus and Core Audio AAC.