I have a video file in MKV format. I like the quality of the video, but I dislike having the audio in FLAC format since I decided it takes up too much space.
It is a dual audio file—it’s an anime with Japanese and English audio—and it has several subtitle streams inside as well.
This is the command I use:
ffmpeg -i "01.mkv" -c:v copy -c:a ac3 -c:s copy "test.mkv"However it only gets the first audio and first subtitle string. I need help with the map option for multiple streams.
63 Answers
I believe you need to specify the mapping of the audio and subtitle streams to ensure that all of them are copied through rather than the first. To do so you need to add -map 0:a? -map 0:s? -map 0:v before your -c:v
This should make your command
ffmpeg -i "01.mkv" -map 0:a? -map 0:s? -map 0:v -c:v copy -c:a ac3 -c:s copy "test.mkv"The map command is used to tell it that you definitely want those things to be pulled through to the output. -map 0:a:1 would specify only to copy audio stream number 1, while -map 0:a? should effectively wildcard it and copy them all.
Add -map 0 after the input, which includes in the output all streams of all types:
ffmpeg -i "01.mkv" -map 0 -c:v copy -c:a ac3 -c:s copy "test.mkv"You can also tell the map command to include only some stream types.
-map 0:a would copy all audio streams and -map 0:a:1 would copy only the first audio stream.
If you have input that may or may not have a stream of that type, append ? at the end (i.e. -map 0:a?).
| Type | Matches |
|---|---|
| v | Video |
| V | Video except attached pictures, video thumbnails, cover arts |
| a | Audio |
| s | Subtitles |
| d | Data |
| t | Attachments |
Just use "-map 0 -scodec copy" instead of having to specify the [v]ideo, [a]udio, and [s]ubtitles manually with all these options. Works for me.
From the documentation:
For example, to map ALL streams from the first input file to output
ffmpeg -i INPUT -map 0 output
The command I use to convert H.265 videos to H.264 (while leaving the audio and subtitles alone) is:
ffmpeg -i source.mkv -vcodec h264 -acodec copy -scodec copy -map 0 output.mkv
Try it!
