decode_flac

Playing around doing a flac decoder implementation. For now, it only output pcm in an output file or on the standard output.

Building

Typing make should do the trick. The built binary should be in the bin directory. You can tweak the makefile to add the STEREO_ONLY macro to compile a version supporting only stereo channel assignments (LEFT_RIGHT, LEFT_SIDE, RIGHT_SIDE, MID_SIDE).

Usage

To use it, you have to give it a flac file as first argument. If there is no second argument or if it is -, the pcm stream is outputted on the standard output. Else the second argument should be the output file.

You can check the md5 sum of the outputted pcm against the md5 sum provided in the metadata of the flac file. To do that you can type:
$ ./bin/decode_flac_to_pcm some_flac_file.flac some_flac_file.pcm && md5sum some_flac_file.pcm
or
$ ./bin/decode_flac_to_pcm some_flac_file.flac | md5sum
and compare the md5 sums.

You can play the outputed pcm with aplay. For flac encoded from a cd, you can type:
$ ./bin/decode_flac_to_pcm some_flac_file.flac | aplay -f cd -
or use the bash script play_flac.sh:
$ PATH=$PATH:./bin/; export PATH; ./play_flac.sh some_flac_file.flac some_other_flac_file.flac

Some options are available:

• --big-endian: output pcm with big endian order. To compare the md5 sums, you can output big endian order pcm with mplayer for example:
  mplayer -ao pcm:nowaveheader:file=some_filename.pcm -format s16be some_flac_file.flac
  Be sure to match the number of bits per sample though.

• --unsigned: output pcm with unsigned samples. To compare the md5 sums, you can output unsigned samples pcm with mplayer for example:
  mplayer -ao pcm:nowaveheader:file=some_filename.pcm -format u16le some_flac_file.flac
  Be sure to match the number of bits per sample though. You can combine these options.

• --input-size bytes: define the size of the input buffer. Should be greater than 42.

• --max-output-size: define the maximum size of the output buffer. It will be truncated to a multiple of the number of bits per sample times the number of channels.

• -i: add a pause capability by pressing enter.

• -q: suppress all informatinal outputs.