In article <BA97E057476044F0905247185C0EB989@vasonote>, Vangelis forthnet <northmed...@the.forthnet.gr> wrote: > On Thu Aug 18 10:06:01 BST 2016, Jim web wrote:
> > I've been told that the root cause is that these use HE-AAC which the > > MPEG2 TS spec can't correctly describe. So it is called aac-lc and it > > is left to the client program to recognise the actual codec. FWIW I was told the above by someone at the BBC who I'd expect to know. However they may be wrong. He and I were referring specifically to the 1280x720 50fps streams obtained by hvfhd. The point that was made to me is that the actual audio is HE but is *misdescribed* in the headers because the header can't correctly describe this. So it relies on the renderer/client to spot what the data format really is. >[snip] > The 50fps hvf modes, > hvfsd, hvfhd > (which are derived from "iptv-all" mediaset) have their audio stream > encoded as AAC LC @128kbpsABR > so Spectral Band Replication IS NOT USED on those (that is why the > encode has increased "transparency"). I also do see it reported as LC when I use ffprobe. But I have been told the above by someone at the BBC. They may be wrong. It seems an odd thing for him to say if it is wrong, though. I may also have misunderstood what he wrote, though, so I'll see if I can check with him. Jim -- Electronics http://www.st-and.ac.uk/~www_pa/Scots_Guide/intro/electron.htm Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html Audio Misc http://www.audiomisc.co.uk/index.html _______________________________________________ get_iplayer mailing list get_iplayer@lists.infradead.org http://lists.infradead.org/mailman/listinfo/get_iplayer