Transcoding live streams question

[John Warburton]

Hello,

Many, many thanks to all who contributed to restoring get_iplayer. I
mentioned elsewhere that my old machine's graphics card can't use
hardware acceleration from the browser-based iPlayer, but piping
get_iplayer.pl into the mpv player gives me smooth pictures at
1280x720 expanded to full screen every time. We use get_iplayer every
day for this kind of thing at home.

With every iteration of get_iplayer, I remove the default ffmpeg
recoding for live streams. This is switched off manually within the
Perl code by me (patch below) because picture quality suffers and the
CPU is exercised more.

But I wonder: (1) am I neglecting a command-line option to do this,
and (2) is there a reason for this recoding that has escaped me?

--- ./orig/get_iplayer.pl    2015-06-03 15:47:12.428924100 +0100
+++ ./patched/get_iplayer.pl 2015-06-03 13:07:23.981928400 +0100
@@ -10464,7 +10464,7 @@
                        push @cmdopts, ( '-vb', "${vb}k" ) if $vb;
                        #push @cmdopts, ( '-vcodec', 'h264' );
                        push @cmdopts, ( '-ab', "${ab}k" ) if $ab;
-                       push @cmdopts, ( '-acodec', 'aac', '-strict',
'experimental' );
+                       push @cmdopts, ( '-acodec', 'copy', '-vcodec',
'copy', '-strict', 'experimental' );
                } else {
                        push @cmdopts, ( '-vn' );
                        push @cmdopts, ( '-acodec', 'copy' );