[FFmpeg-user] [POSSIBLE BUG] Why I can't set -max_prediction_order parameter to its default value 8?

Барт Гопник bart.gopnik at gmail.com
Thu Jul 3 07:55:16 CEST 2014

>> I compress pcm_s16le 44100 Hz 2 channels audio. Default value of "-compression_level" parameter for "flac" encoder is "5". This means that default value of "-max_prediction_order" parameter for "flac" encoder is "8".

< Not if you set lpc_type to fixed.

>> FFMPEG says that "invalid max prediction order: 8". Why?

< For lpc_type fixed, max_prediction_order is limited to 4.

Where can I found info about limitation of each parameters for each
value of other parameters?

>> If I set "-lpc_type" parameter to value "fixed" and set "-min_prediction_order" parameter to value "0" all is OK, but if I explicitly set also "-max_prediction_order" parameter to its default value "8"

< (Why do you believe that max_prediction_order defaults to 8?)

Please look at console outputs again. If I set "-lpc_type" parameter
to value "fixed" (e.g. ffmpeg -loglevel debug -i input.wav -lpc_type
fixed output.flac) FFMPEG says:

[flac @ 0000000000350240]  compression: 5
[flac @ 0000000000350240]  lpc type: Fixed pre-defined coefficients
[flac @ 0000000000350240]  prediction order: 1, 8
[flac @ 0000000000350240]  order method: estimate
[flac @ 0000000000350240]  partition order: 0, 8
[flac @ 0000000000350240]  block size: 4608
[flac @ 0000000000350240]  lpc precision: 15

Please look at 1st and 3rd strings. It mean that "lpc_type" is "fixed"
and "max_prediction_order" is "8" (simultaneously).

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