OT: Help with Broken Downloads Please

[Vangelis forthnet]

On Tue Dec 22 18:34:46 BST 2015, Budge wrote:

> This tells me to use aac_adtstoasc to fix it
> but as usual  cannot quite get the command.
> What is the -bsf:a aac_adtstoasc command,
> or rather where does it fit in total command string?

Hi :-)
Have been out all day to enjoy the great weather
(spring-like sunshine with 16 Celsius), so I was not
able to pick this from the start... :-(

1. It appears your "audio" files are somehow
the result of a failed transcoding from AAC to MP3;
the file extension was correctly set as ".mp3",
but the file content (RAW audio stream) is still left as AAC.
Probably the culprit had been FFmpeg when the
radio programme was initially downloaded...
It appears you then tagged the file with "EasyTAG",
this could have made things worse if EasyTAG
was instructed to tag a seemingly MP3 file which
was in essence an AAC file/stream...

Many times in the past I recommended you install
MediaInfo for your OS:
https://mediaarea.net/nn/MediaInfo/Download
a plea refreshed by batguano999 in this thread...
You should really do it now as you read this,
it's a fine tool and the info it provides (much more
useful than FFmpeg & FFprobe outputs) could
help us (and you) debug future media-related issues
you report on this list...
Please install now and post the report it generates
on the problem audio files...

2. First try the "easy" approach by simply changing the
extension of the problem files from ".mp3" to ".m4a";
this may or (most probably) may not fix the playback issue,
but you should keep the ".m4a" file extension if you are to
process the file further with FFmpeg or other tool...

Your attempt so far with FFmpeg has produced the following error:

[aac @ 0xf36e40] Error decoding AAC frame header.

which is what concerns me the most; anyhow,

3. Try to remux (using the "renamed" file) in one step
to see how it goes:
Rename "problem.mp3" to "problem.m4a"

ffmpeg -i "problem.m4a" -vn -c:a copy -bsf:a aac_adtstoasc -f ipod 
"problem-remuxed.m4a"

I have good suspicion that "problem.m4a"
should really rather be "problem.aac", i.e. RAW
AAC audio stream not yet muxed to the MP4 container...
It may also be  "problem.flv", i.e. RAW
AAC audio stream still inside the FLV container as fetched
by rtmpdump; unsure without the MediaInfo report...
In any case, and pending your further report, try a two-step remux:

ffmpeg -i "problem.m4a" -vn -c:a copy -f adts "problem.aac"

If that succeeds, then continue by issuing:

ffmpeg -i "problem.aac" -vn -c:a copy -bsf:a aac_adtstoasc -f ipod 
"problem-remuxed.m4a"

and hopefully that would play fine...

Regards...

(..any news on those Tea Cakes?
I'm a coffee person myself, but I bet they'd
go down fine with coffee, too...)