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Why is exif incorrect for audio recordsdata and why is audio taking part in as twice as lengthy on iOS with second half being silence?


I’m going through an odd challenge associated to audio recordsdata on iOS. The abstract of the problem is that audio recordsdata within the Recordsdata app in addition to third social gathering music apps like Readdle’s Paperwork app are taking part in as twice as lengthy with the primary half being the precise audio and the second half being silence. The identical audio recordsdata do not have this challenge on macOS. Whereas this can be some bug in yt-dlp, I’m extra inquisitive about what precisely within the audio file is inflicting it to be twice as lengthy as a result of exiftool does not present such challenge and reveals the right period.

For instance, here is a free youtube video I obtain utilizing yt-dlp:

https://youtu.be/V66PMeImkxI

I obtain the audio of it utilizing this command:

yt-dlp -4 -f 'bestaudio[ext=m4a]' "https://youtu.be/V66PMeImkxI"

I’ve uploaded this audio file right here:

https://filetransfer.io/data-package/tJ0sAxx9#hyperlink

On macOS, it appropriately performs as round 4.39 second lengthy audio:

enter image description here

This is the exiftool output confirming 4.39 s period:

exiftool /Customers/XXXXXX/Downloads/Quick Jingle Sound Impact [V66PMeImkxI].m4a 
ExifTool Model Quantity         : 12.04
File Title                       : Quick Jingle Sound Impact [V66PMeImkxI].m4a
Listing                       : /Customers/XXXXXX/Downloads
File Measurement                       : 70 kB
File Modification Date/Time     : 2020:01:27 02:42:30-05:00
File Entry Date/Time           : 2024:05:23 16:03:42-04:00
File Inode Change Date/Time     : 2024:05:23 15:56:22-04:00
File Permissions                : rw-r--r--
File Kind                       : MP4
File Kind Extension             : mp4
MIME Kind                       : video/mp4
Main Model                     : Unknown (sprint)
Minor Model                   : 0.0.0
Appropriate Manufacturers               : iso6, mp41
Film Header Model            : 0
Create Date                     : 2020:01:27 07:42:29
Modify Date                     : 2020:01:27 07:42:29
Time Scale                      : 44100
Length                        : 4.39 s
Most popular Charge                  : 1
Most popular Quantity                : 100.00%
Preview Time                    : 0 s
Preview Length                : 0 s
Poster Time                     : 0 s
Choice Time                  : 0 s
Choice Length              : 0 s
Present Time                    : 0 s
Subsequent Observe ID                   : 2
Observe Header Model            : 0
Observe Create Date               : 2020:01:27 07:42:29
Observe Modify Date               : 2020:01:27 07:42:29
Observe ID                        : 1
Observe Length                  : 4.39 s
Observe Layer                     : 0
Observe Quantity                    : 100.00%
Matrix Construction                : 1 0 0 0 1 0 0 0 1
Media Header Model            : 0
Media Create Date               : 2020:01:27 07:42:29
Media Modify Date               : 2020:01:27 07:42:29
Media Time Scale                : 44100
Media Length                  : 4.39 s
Media Language Code             : eng
Handler Kind                    : Audio Observe
Handler Description             : ISO Media file produced by Google Inc.
Audio Format                    : mp4a
Audio Channels                  : 2
Audio Bits Per Pattern           : 16
Audio Pattern Charge               : 44100
Stability                         : 0
Film Fragment Sequence         : 1
Media Information Measurement                 : 70235
Media Information Offset               : 1536
Avg Bitrate                     : 128 kbps

Subsequent, I Airdrop this file to my iPhone. Within the Recordsdata app, this audio file is taking part in as round 9 second lengthy as a substitute of the unique 4.39 second period. Additionally discover on the backside of this screenshot that the second half within the visualizer is simply silence:

enter image description here

I’ve just a few questions:

  1. What’s inflicting this bug?
  2. Why is exiftool displaying the 4.39s period?
  3. The place’s the silence a part of the audio knowledge coming from?

I’m principally making an attempt to know why can the exif not be trusted?



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