Can't extract mp3 audio from video with ffmpeg

Question

My input is a .mp4 video file.

Try #1

ffmpeg -i pipe:0 -y -map a media/73.mp3

Error:

ffmpeg version 3.3.3 Copyright (c) 2000-2017 the FFmpeg developers
  built with Apple LLVM version 8.1.0 (clang-802.0.42)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/3.3.3 --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-libmp3lame --enable-libx264 --enable-libxvid --enable-opencl --enable-videotoolbox --disable-lzma --enable-vda
  libavutil      55. 58.100 / 55. 58.100
  libavcodec     57. 89.100 / 57. 89.100
  libavformat    57. 71.100 / 57. 71.100
  libavdevice    57.  6.100 / 57.  6.100
  libavfilter     6. 82.100 /  6. 82.100
  libavresample   3.  5.  0 /  3.  5.  0
  libswscale      4.  6.100 /  4.  6.100
  libswresample   2.  7.100 /  2.  7.100
  libpostproc    54.  5.100 / 54.  5.100
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x7f977d800000] stream 1, offset 0xa8: partial file
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x7f977d800000] Could not find codec parameters for stream 0 (Video: h264 (avc1 / 0x31637661), none(smpte170m/smpte170m/bt709), 320x176, 300 kb/s): unspecified pixel format
Consider increasing the value for the 'analyzeduration' and 'probesize' options
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'pipe:0':
  Metadata:
major_brand     : mp42
minor_version   : 0
compatible_brands: mp42isomavc1
creation_time   : 2012-03-13T08:58:06.000000Z
encoder         : HandBrake 0.9.6 2012022800
  Duration: 00:00:10.03, bitrate: N/A
Stream #0:0(und): Video: h264 (avc1 / 0x31637661), none(smpte170m/smpte170m/bt709), 320x176, 300 kb/s, 25 fps, 25 tbr, 90k tbn, 180k tbc (default)
Metadata:
creation_time   : 2012-03-13T08:58:06.000000Z
  encoder         : JVT/AVC Coding
Stream #0:1(und): Audio: aac (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 160 kb/s (default)
Metadata:
  creation_time   : 2012-03-13T08:58:06.000000Z
Stream #0:2(und): Audio: aac (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 160 kb/s
Metadata:
  creation_time   : 2012-03-13T08:58:06.000000Z
Stream #0:3(und): Subtitle: mov_text (text / 0x74786574), 0 kb/s
Metadata:
  creation_time   : 2012-03-13T08:58:06.000000Z
Stream mapping:
  Stream #0:1 -> #0:0 (aac (native) -> mp3 (libmp3lame))
  Stream #0:2 -> #0:1 (aac (native) -> mp3 (libmp3lame))
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x7f977d800000] stream 1, offset 0xa8: partial file
pipe:0: Invalid data found when processing input
Finishing stream 0:0 without any data written to it.
Finishing stream 0:1 without any data written to it.
[mp3 @ 0x7f977b846800] Invalid audio stream. Exactly one MP3 audio stream is required.
Could not write header for output file #0 (incorrect codec parameters ?): Invalid argument
Error initializing output stream 0:1 -- 
Conversion failed!

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Try #2

ffmpeg -i pipe:0 -y -vn -acodec copy media/72.mp3

Error:

[...]
[mp3 @ 0x7febed835200] Invalid audio stream. Exactly one MP3 audio stream is required.
Could not write header for output file #0 (incorrect codec parameters ?): Invalid argument

---

Try #3

ffmpeg -i pipe:0 -y -codec:a libmp3lame -qscale:a 2 media/74.mp3

No error with ffmpeg, but the file is invalid (it's size is 334 bytes)

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Try #4

ffmpeg -i pipe:0 -y -vn -acodec mp3 media/78.mp3

No error with ffmpeg, but the file is invalid (it's size is 334 bytes)

---

Try #5

ffmpeg -f mp4 -i pipe:0 -y media/80.mp3

No error with ffmpeg, but the file is invalid (it's size is 334 bytes)

---

What am I doing wrong? This seems like a fairly easy thing to do...

Answer 1

FFmpeg can't update metadata in WAVE files when output is written over a non-seekable protocol like a pipe. Quicktime seems to rely on metadata to determine file validity. You have to write to file or some other seekable protocol.

Please refer to this question.

Answer 2

All is said by backendscript in http://www.backendscript.com/blog/article/solved-ffmpeg-invalid-audio-stream-exactly-one-mp3-audio-stream-is-required

An aac audio stream requires a dedicated aac container ! As a mp3 udio stream requires a dedicated mp3 container ! This error occurs when we trying to store an AAC stream in an MP3 container. To resolve this change the extension of output file from .mp3 to .aac

Generate error Invalid audio stream. Exactly one MP3 audio stream is required.

ffmpeg -i input.mp4 -vn -acodec copy output.mp3

Working fine

ffmpeg -i input.mp4 -vn -acodec copy output.aac

Answer 3

Try this for extract .mp3:

ffmpeg -i video.mp4 -map 0:a -acodec libmp3lame out.mp3

And maybe this useful for extract .m4a:

ffmpeg -i video.mp4 -map 0:a -c copy out.m4a