Review Request: Fix Transcoding to iPods/iPhone with ffmpeg > 0.10

[Julian Simioni]

> On May 3, 2012, 8:40 p.m., Matěj Laitl wrote:
> > Thanks for the patch, it indeed doesn't work with newer ffmpeg, I faced this too, but was too lazy to fix it. However, from what I've seen -map_meta_data was just renamed to -map_metadata and I don't know if it is enabled by default. Could you please point me to the relevant poiece of ffmpeg documentation that says so? If it is confirmed, I'll be happy to merge this.
> 
> Matěj Laitl wrote:
>     ...the transcoding doesn't work with newer ffmpeg, the patch is fine. (sorry for bad wording)

There is indeed a map_metadata option that performs a similar task to map_meta_data. However it also has a different syntax (it uses integer file indexes instead of filenames). From the ffmpeg manual :

-map_metadata[:metadata_spec_out] infile[:metadata_spec_in] (output,per-metadata)
           Set metadata information of the next output file from infile. Note that those are file indices
           (zero-based), not filenames.  Optional metadata_spec_in/out parameters specify, which metadata to
           copy.


And a little bit below that:
By default, global metadata is copied from the first input file, per-stream and per-chapter
           metadata is copied along with streams/chapters. These default mappings are disabled by creating
           any mapping of the relevant type.


I did test this and at least for converting from FLAC to ALAC it works as expected. I believe these options only exist for more complex file types such as a .mkv file with video and multiple audio streams (say multiple languages or number of channels). As far as I can tell, for simply transcoding audio, we shouldn't have to worry about any of this, but if someone can think of a counterexample I'm sure we can make it work.


- Julian


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On May 3, 2012, 11:07 a.m., Julian Simioni wrote:
> 
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> 
> (Updated May 3, 2012, 11:07 a.m.)
> 
> 
> Review request for Amarok.
> 
> 
> Description
> -------
> 
> While it seemed to work a while ago (before it was merged to trunk), I recently found that the new ipod manager cannot transcode tracks when sending them to my iPod. I spent some time debugging it and was able to find the cause:
> 
> The -map_meta_data option was depricated as of ffmpeg 0.7 and removed in 0.10. Additionally, as far as I can tell the options specified did nothing but explicitly confirm the default option of copying infile metadata to outfile metadata. Please let me know if I'm mistaken about this conclusion.
> 
> I also made some small changes to the debug output that should make things slightly cleaner. 
> 
> When pulling, please use branch fixTranscode at git://github.com/orangejulius/amarok.git as it has separate commits ready to go :)
> 
> 
> Diffs
> -----
> 
>   src/transcoding/TranscodingJob.cpp 5b30c44 
> 
> Diff: http://git.reviewboard.kde.org/r/104839/diff/
> 
> 
> Testing
> -------
> 
> Tested transcoding FLAC music files to ALAC while copying to my iPod classic 160GB
> 
> 
> Thanks,
> 
> Julian Simioni
> 
>

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