Changes between Version 5 and Version 6 of audio types

Timestamp:

Aug 4, 2017, 11:11:58 AM (9 years ago)

Author:

slhck

Comment:

style and some improvements

audio types

@@ -1 @@
-Raw audio in FFmpeg can take several different "forms"
+= Audio Types =
 
-for instance:
+FFmpeg can read various raw audio types (sample formats) and demux or mux them into different containers (formats). For example, you can read and write raw PCM audio into a WAV container.
 
-* pcm_s16le PCM means "traditional wave like format" (raw bytes, basically).  16 means 16 bits per sample, "le" means "little endian", s means "signed", u would mean "unsigned"
+== Sample Formats ==
 
-You can see a list, by running a command like this on your own local box:
+Raw audio in FFmpeg can take several different "forms", i.e. sample formats. For instance:
+
+* `s` means "signed" (for the integer representations), `u` would mean "unsigned"
+* 16 means 16 Bits per sample
+* `le` means "little endian" coding for the samples
+
+You can see a list of supported sample formats by inspecting the `ffmpeg -formats` output:
 
 {{{
 $ ffmpeg -formats | grep PCM
-ffmpeg version N-44123-g5d55830 Copyright (c) 2000-2012 the FFmpeg developers
  DE alaw            PCM A-law
  DE f32be           PCM 32-bit floating-point big-endian
@@ -32 +37 @@
 }}}
 
-Basically these represent all the raw audio type combination possibilities. 
+These represent all the built-in raw audio sample formats.
+
+== Reading and Writing Raw Audio ==
 
 FFmpeg can take input of raw audio types by specifying the type on the command line.  For instance, to convert a "raw" audio type to a ".wav" file:
 
-{{{ ffmpeg -f pcm_s32le input_filename.raw output.wav }}}
+{{{
+ffmpeg -f pcm_s32le input_filename.raw output.wav
+}}}
 
 You can specify number of channels, etc. as well, ex:
 
-{{{ ffmpeg -f u16le -ar 44100 -ac 1 -i input.raw output.wav }}}
+{{{
+ffmpeg -f u16le -ar 44100 -ac 1 -i input.raw output.wav
+}}}
 
-The default for encoding .wav files it uses is pcm_s16le, you can change it by specifying an "acodec" and using the .wav file extension:
+The default for muxing into WAV files is `pcm_s16le`. You can change it by specifying the audio codec and using the WAV file extension:
 
-{{{ ffmpeg -i input -acodec pcm_s32le output.wav }}}
+{{{
+ffmpeg -i input -c:a pcm_s32le output.wav
+}}}
 
-Which will create a .wav file containing audio with that codec (not a raw file) (there are also other containers that can contain raw audio packets, like pcm_bluray).  If you want to create a raw file, don't use the ".wav" ending:
+which will create a WAV file containing audio with that codec (not a raw file). There are also other containers that can contain raw audio packets, like `pcm_bluray`.
 
-{{{ ffmpeg -i input -f s16le -acodec pcm_s16le output.raw }}}
+If you want to create a raw file, don't use the WAV format, but the raw one (as seen in the table above), e.g. `s16le`, and the appropriate audio codec:
 
-You can tell what encoding by this part of your output, if it says ", s16le" then it's raw, it it says ", wav," then it's wav.
-
-{{{ > >> Output #0, s16le, to 'out.2.raw' }}}
+{{{ ffmpeg -i input -f s16le -c:a pcm_s16le output.raw }}}