Recording video and audio with AAC audio codec don't play back correctly in Windows Media Player or Quicktime on macOS

How to reproduce

• Build and run the "Camera Example" on Windows (or on macOS)
• Switch to "Video" mode
• Settings: Either keep the "Default audio codec" or set to "Advanced Audio Codec (AAC)" - both create the same file format.
• Record a video file and make some noise.
• Play back the video in Windows Media Player (without any additional codecs/packs installed) or with Quicktime on macOS
• There is no audio!

ffprobe the video

ffprobe of the generated file results in:

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'video_0004.mp4':
[...]
  Duration: 00:00:04.35, start: 0.000000, bitrate: 3924 kb/s
  Stream #0:0[0x1](und): Audio: aac (mp4a / 0x6134706D), 16000 Hz, mono, fltp, 54 kb/s (default)
[...]
  Stream #0:1[0x2](und): Video: h264 (Constrained Baseline) (avc1 / 0x31637661), yuv420p(progressive), 1280x720, 3905 kb/s, SAR 1:1 DAR 16:9, 30.20 fps, 60 tbr, 30k tbn [...]

Reencoding audio using ffmpeg works

Interestingly, reencoding the audio of the generated file using ffmpeg.exe -i video_0004.mp4 -acodec aac -vcodec copy video_0004_reencoded.mp4 results in a file that plays back correctly in Windows Media Player and Quicktime on macOS.

The reencoded file's ffprobe output is:

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'C:\Users\ChristophNiederberge\Videos\video_0004_reencoded.mp4':
[...]
  Duration: 00:00:04.35, start: 0.000000, bitrate: 3924 kb/s
  Stream #0:0[0x1](und): Video: h264 (Constrained Baseline) (avc1 / 0x31637661), yuv420p(progressive), 1280x720, 3875 kb/s, SAR 1:1 DAR 16:9, 29.97 fps, 60 tbr, 30k tbn 
[...]
  Stream #0:1[0x2](und): Audio: aac (LC) (mp4a / 0x6134706D), 16000 Hz, mono, fltp, 54 kb/s (default)
[...]

With the subtle but important difference of having a `aac (LC)` instead of the `aac` as audio codec information.

Attachments

• video_0004.mp4 is the original recording
• video_0004_reencoded.mp4 is the video reencoded with ffmpeg

Notes

• Playback of the videos works correctly in VLC both on Windows and macOS
• This is independent of the container format
• This is independent of the video codec
• This is independent of the video resolution
• This is independent of the encoding quality or bitrate settings
• This seems to be independent of the audio sample rate