FFmpeg - Audio Channel Layout - Revision history

Dex at 14:40, 14 March 2026

2026-03-14T14:40:21Z

← Older revision		Revision as of 14:40, 14 March 2026
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	== Summary ==		== Summary ==
	This article explains how FFmpeg understands, manipulates, converts, and remaps audio channels.		This article explains how FFmpeg understands, manipulates, converts, and remaps audio channels (e.g., Stereo, 5.1, 7.1). It covers layouts, downmixing, upmixing, channel mapping, and how to explicitly control audio routing using FFmpeg filters such as ''pan'', ''channelmap'', and ''aresample''.

	== Why Channel Layout Matters ==		== Why Channel Layout Matters ==
	Modern multimedia workflows often involve ~~mixed~~ devices and formats.		Modern multimedia workflows often involve a mixture of devices and formats:
			* Surround sound sources (5.1 / 7.1)
			* Stereo-only playback systems
			* Mobile devices with mono speakers
			* Incorrectly labelled or inconsistently ordered tracks
			* Broadcast, film, and online workflows requiring predictable channel order

			A correct channel layout ensures voices remain centred, surround effects are preserved, LFE is handled appropriately, and no channels are lost or duplicated.

	== Understanding FFmpeg’s Channel Layouts ==		== Understanding FFmpeg’s Channel Layouts ==
	Common ~~layouts include~~ mono, ~~stereo~~, 5.1, 7.1.		FFmpeg recognises channel layouts by both name and bitmask.

			=== Common Layout Names ===
			* mono
			* stereo (FL, FR)
			* 3.0 (L, R, C)
			* 4.0 (L, R, SL, SR)
			* 5.0 (L, R, C, SL, SR)
			* 5.1 (L, R, C, LFE, SL, SR)
			* 7.1 (L, R, C, LFE, SL, SR, BL, BR)

			=== Inspecting an Input File ===
			ffmpeg -i input.mkv

	== Downmixing Surround to Stereo ==		== Downmixing Surround to Stereo ==
	~~Examples of downmix commands~~.		=== Default Downmix ===
			ffmpeg -i input.mkv -ac 2 output.mp4

			=== Custom Downmix Matrix ===
			ffmpeg -i input-5.1.wav -filter_complex "pan=stereo\|FL = 0.90FL + 0.32FC + 0.22SL + 0.22BL\|FR = 0.90FR + 0.32FC + 0.22SR + 0.22BR" output.wav

	== Upmixing Stereo to Surround ==		== Upmixing Stereo to Surround ==
	~~Example:~~ stereo to 5.1.		=== Basic Upmix ===
			ffmpeg -i stereo.wav -af "channelmap=channel_layout=5.1" output.wav

			=== Enhanced Upmix ===
			ffmpeg -i stereo.wav -filter_complex "pan=5.1\|FL=FL\|FR=FR\|C=0.5FL+0.5FR\|SL=FL\|SR=FR\|LFE=0" output.wav

	== Reordering Channels (channelmap) ==		== Reordering Channels (channelmap) ==
	~~Example: correcting~~ wrong order.		ffmpeg -i wrong-order.wav -filter_complex "channelmap=map=0\|1\|4\|5\|2\|3:channel_layout=5.1" fixed.wav

	== Extracting Individual Channels ==		== Extracting Individual Channels ==
	~~Examples using~~ -map_channel.		ffmpeg -i input.wav -map_channel 0.0.0 FL.wav
			ffmpeg -i input.wav -map_channel 0.0.1 FR.wav
			ffmpeg -i input.wav -map_channel 0.0.2 FC.wav
			ffmpeg -i input.wav -map_channel 0.0.3 LFE.wav

	== Creating Silent Placeholder Channels ==		== Creating Silent Placeholder Channels ==
	~~Example using~~ anullsrc.		ffmpeg -f lavfi -i anullsrc=channel_layout=5.1:sample_rate=48000 silence.wav

	== Common Pitfalls ==		== Common Pitfalls ==
	~~Includes~~ layout ~~mismatches and~~ LFE ~~issues~~.		=== Invalid Layouts ===
			Occurs when channel count mismatches layout.

			=== LFE Issues ===
			LFE may be discarded or reduced in downmixes.

			=== Wrong Surround Ordering ===
			Rear vs side channels may be swapped.

	== Design & Architecture Considerations ==		== Design & Architecture Considerations ==
	Always explicitly declare layouts.		* Always explicitly declare layouts.
			* Avoid relying on defaults.
			* Document downmix matrices.
			* Test with both headphones and speakers.

	== Troubleshooting Checklist ==		== Troubleshooting Checklist ==
	~~Use~~ ffprobe ~~to inspect layouts~~.		ffprobe -show_streams input.wav

	== Related Topics ==		== Related Topics ==

Dex at 14:37, 14 March 2026

2026-03-14T14:37:25Z

@@ Line 2: / Line 2: @@
 [[Category:FFmpeg]]
 [[Category:Multimedia]]
-Reference: [[https://superuser.com/questions/852400/properly-downmix-5-1-to-stereo-using-ffmpeg superuser: Properly downmix 5.1 to stereo using ffmpeg]]<br/>
-Reference: [[https://trac.ffmpeg.org/wiki/AudioChannelManipulation FFmpeg: Manipulating audio channels]]
+'''References:'''

Dex: Created page with "Category:Software Category:FFmpeg Category:Multimedia Reference: https://superuser.com/questions/852400/properly-downmix-5-1-to-stereo-using-ffmpeg superuser: Properly downmix 5.1 to stereo using ffmpeg
Reference: https://trac.ffmpeg.org/wiki/AudioChannelManipulation FFmpeg: Manipulating audio channels"

2025-03-12T14:13:54Z

Created page with "Category:Software Category:FFmpeg Category:Multimedia Reference: https://superuser.com/questions/852400/properly-downmix-5-1-to-stereo-using-ffmpeg superuser: Properly downmix 5.1 to stereo using ffmpeg<br/> Reference: https://trac.ffmpeg.org/wiki/AudioChannelManipulation FFmpeg: Manipulating audio channels"

New page

[[Category:Software]]
[[Category:FFmpeg]]
[[Category:Multimedia]]
Reference: [[https://superuser.com/questions/852400/properly-downmix-5-1-to-stereo-using-ffmpeg superuser: Properly downmix 5.1 to stereo using ffmpeg]]<br/>
Reference: [[https://trac.ffmpeg.org/wiki/AudioChannelManipulation FFmpeg: Manipulating audio channels]]