Issues with Large Files

[RS]

>From: Budge

>Sent: Monday, January 23, 2017 11:45

>You will have to ask somebody who knows about these things but when I 
>chased Linn this is relevant part of the reply:-

>"The issue is heavily influenced by but not directly related to track 
>duration. (Possibly too much technical detail - it's caused by the number 
>of entries in the 'stsz' table. Problem files have huge numbers of entries, 
>often with repeated small values; the mpeg spec allows but doesn't 
>encourage encoders to combine these blocks together.)"

This page describes stsz.
https://wiki.multimedia.cx/index.php/QuickTime_container#stsz
There are two modes, uniform sample size and different sample size.  I 
assume the sample size is the number of bits to encode the level, namely 16. 
If there is a large table it must be because the different sample size flag 
is set.  For a 9200s file the number of sample sizes would be 441,600,000. 
Unless the sampling frequency deviates from 48kHz, the table size is 
directly related to track  duration.  I do not know why the different sample 
size flag should be set; maybe it is the presence of the thumbnail.  You 
could try running it through ffmpeg with -vn -acodec copy.

Interestingly the Linn amplifiers support 24 bit encoding and a sampling 
frequency of 192 kHz, which would make the stsz table 4 times as large.  (As 
the article you linked to said, 192kHz sampling is pointless or even 
counter-productive, and there little to be gained by 24 bit encoding for a 
production version.)

I did ask whether the number of samples per frame was always 1024.  It seems 
it can also be 960 but 1024 is more common.

I thought you had given the name of the opera your Linn player would not 
play, but going back through the thread all I could find was that it was 
9200s, so it is fairly short.  Der Rosenkavalier is just under 5 hours.  I 
downloaded it from dashhigh1 and played it on my Triax satellite receiver, 
which cost a tiny fraction of the cheapest Linn, and it played all through. 
I skipped through it, but it played to the end without problem, as have 
several shorter operas.