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

[nsabbi at fastwebnet.it]

>
>
>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.


no PMT? nice :(


>
>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. 

it's always 1536 for ac3

>Unfortunately, this information is unavailable
>to pes_parse2, so can't be used. 

do you mean that PES_packet_len is 0 for that ac3 pid?

>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)?

unlikely, but may happen

>
>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.

this is a card-indipendent issue

>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)
>


Please, upload a sample to ftp://www.mplayerhq.hu/MPlayer/incoming and
tell us the filename.
Maybe I won't be able to analyze the file (and fix demux_ts) before monday,
because actually I'm bound to a 28.8 modem connection :(

P.S. you can also run mplayer -v -v file.ts >& log and send me the compressed
log.

Thanks,
         Nico