Opened 5 years ago

Last modified 5 years ago

#4883 new defect

Audio with multiple sample rates causes pitch issues

Reported by: TalLevAmi Owned by:
Priority: normal Component: undetermined
Version: git-master Keywords: mov aac
Cc: Blocked By:
Blocking: Reproduced by developer: no
Analyzed by developer: no


Summary of the bug:
Encoding a video whose audio track as two parts one with 44100 and one with 48000 causes pitch issues in one of the parts.

How to reproduce:

% ffmpeg -report -y -i nlpebvbo8gaxpvffcnb6.mp4 -codec:v libx264 -codec:a libfaac -pix_fmt yuv420p -crf 30 out.mp4

Attached is the log file from running with -report.

Attachments (1)

ffmpeg-20150926-233850.log (49.1 KB) - added by TalLevAmi 5 years ago.
log file

Download all attachments as: .zip

Change History (5)

Changed 5 years ago by TalLevAmi

log file

comment:1 Changed 5 years ago by TalLevAmi

Sample uploaded to ftp as multiple_sample_rates.mp4

comment:2 Changed 5 years ago by cehoyos

  • Keywords mov aac added
  • Version changed from unspecified to git-master

How was the sample created? The aac bitstream signals 48kHz afaict, how is the decoder supposed to know that it is meant to be 44100? Or do I misunderstand?

comment:3 Changed 5 years ago by TalLevAmi

I'm trying to determine the source of the video. I'll update when I have more details.

Note that Adobe Media Encoder was able to successfully manipulate this video and it runs properly in QuickTime?.

Also, ffprobe's audio stream is reported with:
"sample_rate": "48000",
"codec_time_base": "1/48000",
"time_base": "1/44100",

comment:4 Changed 5 years ago by TalLevAmi

The video was created using Apple’s AVFoundation framework. Two videos were set together in the timeline, and exported using the default setting for an MP4 (using AVAssetExportSession).

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