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Author Myrsloik
Version r1
Download bas-r1.7z
Category Source filters
License MIT
Discussion Doom9 Thread



A new sample accurate but somewhat slow FFmpeg based audio source filter for AviSynth. No indexing is required.


Syntax and Parameters

BestAudioSource (string "source", int "track", int "adjustdelay", bool "exactsamples", bool "enable_drefs", bool "use_absolute_path", float "drc_scale", string "varprefix")

string  source =
Path to audio file. Path can be omitted if the script is in the same folder as the audio file.

int  track = -1
Positive track numbers refer to the FFmpeg given stream number. Negative numbers refer to the nth audio track with -1 being the first.

int  adjustdelay = -1
Delay adjustment; not yet implemented.

bool  exactsamples = false
Set to true if you want opening files to be really slow but for some reason need a completely sample exact length.

bool  enable_drefs = false
Enable loading of external tracks, disabled by default.

bool  use_absolute_path = false
Allows loading of external tracks via absolute paths, disabled by default.

float  drc_scale = 0.0
Dynamic Range Scale Factor. The factor to apply to dynamic range values from the AC-3 stream. This factor is applied exponentially.
The default value is 0. There are 3 notable scale factor ranges:
  • drc_scale == 0
    DRC disabled. Produces full range audio.
  • 0 < drc_scale <= 1
    DRC enabled. Applies a fraction of the stream DRC value. Audio reproduction is between full range and full compression.
  • drc_scale > 1
    DRC enabled. Applies drc_scale asymmetrically. Loud sounds are fully compressed. Soft sounds are enhanced.

string  varprefix = ""
Works the same as FFMS2.


BestAudioSource("blah.mp4", track=-1, adjustdelay=-1, exactsamples=false, enable_drefs=false, use_absolute_path=false, drc_scale=0)


Version        Date            Changes
r1 2021/09/11 - First release. Everything except automatic delay adjustment implemented. test8 2021/08/17 - Updated with several new options, including drc_scale. test7 2020/08/02 - VapourSynth: update for V4 api again; fixed all known bugs and should be fairly stable test6 2020/06/23 - Fixes clips with more than 2^31 samples in VS and adds 24 bit output to AviSynth. test5 2020/06/13 - Properly export the number of bits per sample test4 2020/06/09 - Update for latest audio api revision test3 2020/01/26 - Fixes the channel mask variable that was previously almost always wrong in AviSynth. - Also add VapourSynth support. test2 2020/01/08 - Fixed output and new parameter "exactsamples" test1 2020/01/07 - Initial release

Archived Downloads

Version Download Mirror
test8 BestAudioSource-test8.7z

External Links

  • GitHub - Source code repository.

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