Majority of m4a files can't decode: "isomp4: missing moov atom"

[cybersoulK]

I made several sounds from audacity and from ffmpeg command line tool.
They play normally on mac and VLC playbacks, but i get this error with Symphonia: Unsupported("isomp4: missing moov atom")

Symphonia/symphonia-format-isomp4/src/demuxer.rs

Line 418 in 4f41954

Reading them with a parser reveals that moov is at the end (which is most common in m4a).
I had a couple of files m4a that worked (first file structure)

which indicates missing crucial functionality to parse m4a

[cybersoulK]

running qt-faststart sound.m4a sound2.m4a for all files solved the issue.
I am not sure if this is just a overlooked feature, or a crate choice.

[tGrothmannFluffy]

Hi there, I am getting the same error message with some m4a files.

[sunaemon]

I've encountered the same "Unsupported("isomp4: missing moov atom")" error, which can be reproduced using the code at https://github.com/sunaemon/missing-moov-atom/blob/main/src/main.rs#L119.

It seems the issue occurs when Symphonia attempts to parse m4a files where the 'moov' atom is placed after the 'mdat' atom in an unseekable MediaSource.

Workarounds:

1. Save the audio data in a Vec and pass it as Box::new(Cursor::new(data.into_boxed_slice())).
2. Save the audio data to a file before processing with Symphonia, then pass it as shown in the "Getting Started" example: https://github.com/pdeljanov/Symphonia/blob/master/symphonia/examples/basic-interleaved.rs#L17-L22

It would be helpful if Symphonia could generate a more user-friendly error message in this scenario, perhaps indicating that the file structure is not currently supported for non-seekable sources. This could guide users towards the workarounds more quickly.