[MPlayer-dev-eng] Ac3 streams detected as LPCM or SPU in TS

[lordvader at swiftdsl.com.au]

Hi. This is my first posting to this list, and my first real attempt at
hacking mplayer :)

I've been playing around with the transport stream demuxer in order to get
ac3
sound working properly for Australian HDTV streams. It has become apparent
that the streams provided are being detected as LPCM streams, and DVD
subtitles rather than a proper ac3 stream.
The dvb card I'm using is the VisionPlus DVB-T, which uses the bt848 chipset.
It also requires "TWINHAN DST based DVB-S frontend" and "Nebula/Pinnacle PCTV
PCI cards". From what I understand, this card does not provide PMT, hence pid
autodetection is required, which is where this falls apart.

If I alter the condition
if((type_from_pmt == AUDIO_A52) ||(p[0] == 0x0B && p[1] == 0x77)) from
pes_parse2 to be true, i get ac3 playback. Of course, this is just a test, as
any subtitles in the stream will then the detected as ac3.

Something I have noticed, is that when an ac3 packet is "found", the packet
size is determined to be 1536. Unfortunately, this information is unavailable
to pes_parse2, so can't be used. This seems to be the best way of properly
detecting the stream, but I was also wondering of the likelyhood of non ac3
packets being of that size too (hence more breakage)?

Also, if there are any Australian users/developers out there with dvb cards,
could you please verify that ac3 is or isn't working? If you're using a card
other than what I'm using, that would be interesting.
I've been using channel 9's test stream, as it is the only full HDTV
stream we
get (1920x1088, plus ac3).

(PS: Sorry is this arrives twice, my email has been screwy of late)