Simon Nash wrote:
richard wrote:
On Sun Apr 10 02 Simon Nash wrote:
I would be interested in trying these on my Linn DS.
I will send you three m4a files off list of Bells on Sunday (2.8Mb each)
downloaded with get_iplayer for you to try. The 3 files are:
Bells1_noscript.m4a
This file does not use Jon's script. The file does not play.
Bells1_noscript_mp4creator.m4a This file does not use Jon's script,
but has been optimized with
mp4creator using:
mp4creator -optimize Bells1_noscript_mp4creator.m4a
The file does not play.
Bells1_script.m4a This file uses Jon's script. The file plays OK.
I also ran the files with AtomicParsley. The results were:
:~/audio$ AtomicParsley Bells1_noscript.m4a -t + free atom space: 2056
padding available: 2048 bytes
user data space: 5700
media data space: 2880808
:~/audio$ AtomicParsley Bells1_noscript_mp4creator.m4a -t +
free atom space: 0
padding available: 0 bytes
user data space: 5700
media data space: 2880808
:~/audio$ AtomicParsley Bells1_script.m4a -t +
free atom space: 0
padding available: 0 bytes
user data space: 5700
media data space: 2880808
Thanks for sending these. I tried them on the Linn DS and they all
played OK. It seems that there is some other issue with the Marantz
that doesn't affect the Linn DS. I'll look at the three files in
more detail to see if I can get any clues from that.
I've narrowed down the vital difference (with a little more help from
Richard). In the DecoderConfigDescriptor within the esds atom, there's
a field named avgBitrate (average bit rate). In the file that doesn't
play, this field is set to zero. In the file that does play, this field
is set to a non-zero value.
I think the most efficient way to get this field set correctly is to
use ffmpeg to create a .aac file and then use mp4creator -optimize to
convert this file to a .mp4 file. This will put the moov atom at the
start of the file, set the esds descriptor lengths using the 4-byte
format, and set the average bitrate field correctly.
I have sent Richard a .mp4 file created in this way for him to try.
Simon
I'd be interested to know how you managed to get a m4a file to play on
my Marantz using only mp4creator. I cannot replicate that. It seems to
need mp4tags to rewrite the metadata atoms to make the file playable.
Unless you know otherwise.
The test files that I sent you were actually created using iTunes and then
patched to remove the iTunes-specific header information. I have verified
that files produced by mp4creator with the -optimize option play OK on the
Linn DS, but it seems that for some reason they don't play on the Marantz.
Simon
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