When you work with videos that have multiple audio tracks or subtitles, leaving everything up to FFmpeg can leave only the streams you never intended to keep. The -map option lets you explicitly choose which video, audio, and subtitle streams to include in the output. This article explains -map through practical examples, from the basic syntax to extracting specific tracks, excluding streams with negative mapping, and combining multiple input files.

Tested with: FFmpeg 6.1 (verified against real FFmpeg) / Target OS: Windows / macOS / Linux

Default Behavior Without -map

If you do not specify -map, FFmpeg automatically selects one “best” stream of each kind:

  • Video: the highest-resolution stream
  • Audio: the stream with the most channels
  • Subtitles: the first compatible subtitle may be selected when the output format and default subtitle encoder support it

To handle multiple audio tracks or specific subtitles, you need -map.

Basic Syntax of -map

-map [input file index]:[stream type]:[stream index]
  • Input file index: the first input is 0, the second is 1, and so on
  • Stream type: v (video), a (audio), s (subtitle), d (data)
  • Stream index: the number within the same type (0-based)

Basic Usage

Select the First Video and First Audio Stream

ffmpeg -i input.mp4 -map 0:v:0 -map 0:a:0 -c copy output.mp4

Copy All Streams (Including Subtitles)

ffmpeg -i input.mkv -map 0 -c copy output.mkv

-map 0 includes every stream from input file 0 in the output.

Inspecting Stream Information

First, check the list of streams in the input file with ffprobe:

ffprobe -v quiet -show_streams -select_streams a input.mkv

Working with Multiple Audio Tracks

Extract Only a Specific Audio Track (the Second One)

ffmpeg -i input.mkv -map 0:v:0 -map 0:a:1 -c copy output_audio1.mp4

Include All Audio Tracks

ffmpeg -i input.mkv -map 0:v -map 0:a -c copy output_all_audio.mp4

Selecting Subtitle Streams

Output with Subtitles Included

ffmpeg -i input.mkv -map 0:v:0 -map 0:a:0 -map 0:s:0 -c copy output_with_sub.mkv

Extract Subtitles Only

ffmpeg -i input.mkv -map 0:s:0 -c:s copy output.srt

Negative Mapping (Excluding Specific Streams)

Prefixing -map with a - lets you exclude that stream:

All Streams Except Subtitles

ffmpeg -i input.mkv -map 0 -map -0:s -c copy output_nosubs.mkv

Specify -map 0 (all streams) followed by -map -0:s (exclude subtitles).

Exclude Only a Specific Audio Track

ffmpeg -i input.mkv -map 0 -map -0:a:1 -c copy output.mkv

Combining Streams from Multiple Input Files

Take the video and audio from two files and merge them into one:

ffmpeg -i video.mp4 -i audio.mp3 -map 0:v:0 -map 1:a:0 -c copy output.mp4

Combine Two Language Audio Tracks into One File

ffmpeg -i video.mp4 -i audio_ja.aac -i audio_en.aac \
  -map 0:v:0 -map 1:a:0 -map 2:a:0 \
  -c copy output_bilingual.mkv

Setting Stream Metadata

To set language tags on streams:

ffmpeg -i input.mkv -map 0 -c copy \
  -metadata:s:a:0 language=jpn \
  -metadata:s:a:1 language=eng \
  output.mkv

Summary of Common Use Cases

GoalCommand
Extract video only-map 0:v:0
Extract audio only-map 0:a:0
Copy all streams-map 0
All streams except subtitles-map 0 -map -0:s
Replace audio from another file-map 0:v -map 1:a

Measured Example

If a 2-minute MKV contains one video stream, two audio streams, and one subtitle stream, -map 0 -c copy copies all streams without re-encoding:

ffmpeg -i input.mkv -map 0 -c copy output_all.mkv

This is mostly remuxing, so on an SSD it often finishes in a few to a dozen seconds. Output size is usually almost identical to the input, though container metadata and indexes can change it by a few MB.

If you copy subtitles from MKV to MP4, the command may fail depending on the subtitle format. For MP4, either omit subtitles or convert them to a supported format. Before delivery, inspect the output with ffprobe and verify audio count, language tags, and channel layout. Results vary by environment.

Primary sources: ffmpeg.org/ffmpeg.html#Stream-specifiers-1 / trac.ffmpeg.org/wiki/Map