Changes between Version 12 and Version 13 of AudioChannelManipulation

Timestamp:

Sep 19, 2014, 12:13:34 AM (12 years ago)

Author:

llogan

Comment:

add -ac 2 example, add statistics section

AudioChannelManipulation

@@ -147 +147 @@
 }}}
 
+Or use `-ac 2` instead of the pan audio filter:
+
+{{{
+ffmpeg -i input1.wav -i input2.wav -filter_complex "[0:a][1:a]amerge[aout]" -map "[aout]" -ac 2 output.mp3
+}}}
+
+{{{
+#!div style="border: 1pt dotted; margin: 1em; background-color: #fffff9;"
+'''Note:''' The output produced with the pan audio filter may not be identical to the output produced with `-ac 2`, so you'll have to listen to your outputs or view [#Statistics audio statistics] to determine which output suits you.
+}}}
+
 == Mix both stereo channels to stereo ==
 
@@ -181 +192 @@
 {{{
 ffmpeg -i stereo.wav -map_channel -1 -map_channel 0.0.1 output.wav
+}}}
+
+----
+
+== Statistics ==
+
+The [https://ffmpeg.org/ffmpeg-filters.html#astats astats audio filter] can display information including length, DC offset, min/max levels, peak/RMS level dB:
+
+{{{
+$ ffmpeg -i input.wav -af astats -f null -
+…
+[Parsed_astats_0 @ 0x168a260] Channel: 1
+[Parsed_astats_0 @ 0x168a260] DC offset: -0.001829
+[Parsed_astats_0 @ 0x168a260] Min level: -0.605072
+[Parsed_astats_0 @ 0x168a260] Max level: 0.607056
+[Parsed_astats_0 @ 0x168a260] Peak level dB: -4.335430
+[Parsed_astats_0 @ 0x168a260] RMS level dB: -20.298984
+[Parsed_astats_0 @ 0x168a260] RMS peak dB: -12.303891
+[Parsed_astats_0 @ 0x168a260] RMS trough dB: -35.352893
+[Parsed_astats_0 @ 0x168a260] Crest factor: 6.283154
+[Parsed_astats_0 @ 0x168a260] Flat factor: 0.000000
+[Parsed_astats_0 @ 0x168a260] Peak count: 2
+[Parsed_astats_0 @ 0x168a260] Channel: 2
+[Parsed_astats_0 @ 0x168a260] DC offset: -0.001826
+[Parsed_astats_0 @ 0x168a260] Min level: -0.585999
+[Parsed_astats_0 @ 0x168a260] Max level: 0.608490
+[Parsed_astats_0 @ 0x168a260] Peak level dB: -4.314931
+[Parsed_astats_0 @ 0x168a260] RMS level dB: -20.519969
+[Parsed_astats_0 @ 0x168a260] RMS peak dB: -12.056472
+[Parsed_astats_0 @ 0x168a260] RMS trough dB: -36.784681
+[Parsed_astats_0 @ 0x168a260] Crest factor: 6.460288
+[Parsed_astats_0 @ 0x168a260] Flat factor: 0.000000
+[Parsed_astats_0 @ 0x168a260] Peak count: 2
+[Parsed_astats_0 @ 0x168a260] Overall
+[Parsed_astats_0 @ 0x168a260] DC offset: -0.001829
+[Parsed_astats_0 @ 0x168a260] Min level: -0.605072
+[Parsed_astats_0 @ 0x168a260] Max level: 0.608490
+[Parsed_astats_0 @ 0x168a260] Peak level dB: -4.314931
+[Parsed_astats_0 @ 0x168a260] RMS level dB: -20.408071
+[Parsed_astats_0 @ 0x168a260] RMS peak dB: -12.056472
+[Parsed_astats_0 @ 0x168a260] RMS trough dB: -36.784681
+[Parsed_astats_0 @ 0x168a260] Flat factor: 0.000000
+[Parsed_astats_0 @ 0x168a260] Peak count: 2.000000
+[Parsed_astats_0 @ 0x168a260] Number of samples: 1440706
 }}}