[FFmpeg-devel] MPEG Audio encoding

John Sigler linux.kernel
Fri Jan 25 18:22:01 CET 2008

Gabriel Bouvigne wrote:

> John Sigler wrote:
>> LAME seems (??) to have removed MP1 support some time ago.
> LAME never had encoding support for MP1

Was it decoding support perhaps?

(Checking the history file...)

LAME 3.95.1    January 12 2004

     * Gabriel Bouvigne:
           o fixed a crash when using vbr-new
           o changed ReplayGain reference level to 89dB

Hey! You wrote that entry :-)

>> [snip MPEG-1 vs MPEG-2 considerations]
> The first set is the MPEG1 sampling freqs, the second set is the
> MPEG2 sampling freqs.

Thanks for clarifying.

>> And mpegaudio.h defines
>> #define MPA_STEREO  0
>> #define MPA_JSTEREO 1
>> #define MPA_DUAL    2
>> #define MPA_MONO    3
>> But joint stereo and dual mono do not seem (??) to be supported by
>> the encoder. Is that correct?
> Last time I checked, only regular stereo was supported.


>> Were joint stereo and dual mono actually defined for Layer II,
>> or did they only show up later in Layer III?
> From memory, I'd say that dual channels is also supported by Layer II
> (anyway, dual channels mode is mainly a matter of semantics).
> Joint stereo is also supported by Layer II, but only in the intensity
> stereo mode (ie no mid/side stereo).

Thanks I will definitely scan 13818-3.

Please correct me if this is nonsense, AFAIU, Intensity stereo coding
is considered less desirable than M/S stereo coding at bitrates in the
128-256 kbit/s range for the MPEG Audio family of codecs?


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