#11275: (Audio) Metadata is wrongly exported and reimported with current format
resulting in data loss
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Reporter: mytait | Type: defect
Status: new | Priority: normal
Component: undetermined | Version: 7.1
Keywords: ffmetadata | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
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Summary of the bug:
i want to export audio metadata using the metadata muxer and reimport it
later after processing and possibly re-enconding.
https://ffmpeg.org/ffmpeg-all.html#ffmetadata
Data is exported but the metadataformat reads only one key=value line at a
time
However, embedded metadata in files can be multi-line: e.g. song lyrics.
that metadata is exported like this:
{{{
;FFMETADATA1
title=test title
artist=test artist
album_artist=test album artits
lyrics=Lyrics line1
Lyricsline2
Lyricsline3
comment=test song
encoder=Lavf61.7.100
}}}
The "Lyricsline2" and "Lyricsline3" are exported to a new line and the
import function ignores them as they seem to be keys without a value.
Therefore the new file ends with only the first line "Lyrics line1".
POSSIBLE FIX
I found out that if i modify the resulting metadata export (it is a text
file) adding unix like line continues then all lyrics are imported
correctly:
{{{
;FFMETADATA1
title=test title
artist=test artist
album_artist=test album artits
lyrics=Lyrics line1\
Lyricsline2\
Lyricsline3
comment=test song
encoder=Lavf61.7.100
}}}
How to reproduce:
{{{
% #extract metadata from mp3 with multiline lyrics to txt file
% ffmpeg -i in_file_embedded.mp3 -c copy -map_metadata 0 -map_metadata:s
0:s -map_metadata:s:a 0:s:a -f ffmetadata 1out_export.txt
#embed metadata to another metadata empty mp3 file
ffmpeg -i in_test_no_metadata.mp3 -f ffmetadata -i 1out_export.txt -c copy
-map_metadata 1 out_embedded.mp3
#extract the metadata again from the new embeddeed file. Lines are missing
ffmpeg -i out_embedded.mp3 -c copy -map_metadata 0 -map_metadata:s 0:s
-map_metadata:s:a 0:s:a -f ffmetadata 2out_export_missinglines.txt
ffmpeg version
ffmpeg version 7.1-full_build-www.gyan.dev
}}}
Patches should be submitted to the ffmpeg-devel mailing list and not this
bug tracker.
--
Ticket URL: <https://trac.ffmpeg.org/ticket/11275>
FFmpeg <https://ffmpeg.org>
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