Opened 8 years ago

Last modified 8 years ago

#4883 new defect

Audio with multiple sample rates causes pitch issues

Reported by: Tal Lev-Ami 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 Tal Lev-Ami 8 years ago.
log file

Download all attachments as: .zip

Change History (5)

by Tal Lev-Ami, 8 years ago

Attachment: ffmpeg-20150926-233850.log added

log file

comment:1 by Tal Lev-Ami, 8 years ago

Sample uploaded to ftp as multiple_sample_rates.mp4

comment:2 by Carl Eugen Hoyos, 8 years ago

Keywords: mov aac added
Version: unspecifiedgit-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 by Tal Lev-Ami, 8 years ago

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 by Tal Lev-Ami, 8 years ago

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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