Changes between Version 9 and Version 10 of AudioChannelManipulation

Timestamp:

Jun 6, 2014, 11:55:13 PM (12 years ago)

Author:

llogan

Comment:

provide more explicit mappings; add standards link; note-ize

AudioChannelManipulation

@@ -23 +23 @@
 }}}
 
+{{{
+#!div style="border: 1pt dotted; margin: 1em; background-color: #fffff9;"
+'''Note:''' Your player will likely play the first stream by default unless your player allows you to select the desired stream.
+}}}
+
 == stereo → 2 × mono files ==
 
@@ -52 +57 @@
 
 {{{
-ffmpeg -i input.mp3 -filter_complex "[0:a][0:a]amerge[aud]" -map "[aud]" output.m4a
-}}}
-
-'''Note:''' These examples will not magically create a "true" stereo output from the mono input, but simply place the same audio into both the `FL` and `FR` channels of the output (both channels will be identical).
+ffmpeg -i input.mp3 -filter_complex "[0:a][0:a]amerge[aout]" -map "[aout]" output.m4a
+}}}
+
+{{{
+#!div style="border: 1pt dotted; margin: 1em; background-color: #fffff9;"
+'''Note:''' These examples will not magically create a "true" stereo output from the mono input, but simply place the same audio into both the left and right channels of the output (both channels will be identical).
+}}}
 
 == 2 × mono → stereo ==
@@ -70 +78 @@
 
 {{{
-ffmpeg -i left.mp3 -i right.mp3 -filter_complex amerge output.mka
+ffmpeg -i left.mp3 -i right.mp3 -filter_complex "[0:a][1:a]amerge[aout]" -map "[aout]" output.mka
 }}}
 
@@ -81 +89 @@
 {{{
 ffmpeg -i front_left.wav -i front_right.wav -i front_center.wav -i lfe.wav -i back_left.wav -i back_right.wav \
--filter_complex "[0:a][1:a][2:a][3:a][4:a][5:a] amerge=inputs=6" output.wav
+-filter_complex "[0:a][1:a][2:a][3:a][4:a][5:a]amerge=inputs=6[aout]" -map "[aout]" output.wav
 }}}
 
@@ -96 +104 @@
 }}}
 
-* By default when using `-ac 2` the LFE channel is omitted.
-* `ffmpeg` integrates a default down-mix (and up-mix) system that should be preferred (the `-ac` option) unless you have very specific needs. 
+{{{
+#!div style="border: 1pt dotted; margin: 1em; background-color: #fffff9;"
+'''Notes:'''
+* By default when using `-ac 2` the LFE channel is omitted. See "[http://www.atsc.org/cms/standards/a_52-2010.pdf Digital Audio Compression Standard (Document A/52:2010)]" for more downmixing info involving LFE.
+* `ffmpeg` integrates a default down-mix (and up-mix) system that should be preferred (the `-ac` option) over the pan filter unless you have very specific needs. 
+}}}
 
 If you want to map specific channels and drop the rest you can use the [https://ffmpeg.org/ffmpeg-filters.html#pan pan audio filter]. This will map the `FL` (Front Left) of the input to the  `FL` of the output, and the `FR` (Front Right) of the input to the `FR` of the output:
@@ -120 +132 @@
 
 {{{
-ffmpeg -i input1.wav -i input2.wav -filter_complex "amerge,pan=stereo:c0<c0+c2:c1<c1+c3" output.mp3
+ffmpeg -i input1.wav -i input2.wav -filter_complex "[0:a][1:a]amerge,pan=stereo:c0<c0+c2:c1<c1+c3[aout]" -map "[aout]" output.mp3
 }}}