[vorbis] retrieving "instant" bitrate without vo_open?
safemode
safemode at speakeasy.net
Sat Sep 22 21:29:22 PDT 2001
On Saturday 22 September 2001 23:41, Michael Smith wrote:
> >How could i do that without vorbisfile? none of the other structures have
> > a bitrate element. That's the problem i'm having.
>
> Ah... Now I see. Ok, vorbisfile is totally useless for this (well, not
> totally. One COULD make it work. But it's not suitable).
>
> You want to use mostly libogg, plus two or three functions from libvorbis.
> You need to read in each packet in order (see the ogg docs or maybe
> decoder_example.c for how to do this). Then, instead of actually decoding
> the packet, use vorbis_packet_blocksize() to get the size (in samples) of
> the packet (see vcut or vorbiscomment for an example of how to use these).
Is none of this documented on the xiph site? i cant find anythnig but ov
functions and some structures. ?
i'm reading through the headers now but what type is packet? ogg_packet has
bytes and ogg_page has body_len .
> Then, you have the length in samples of the packet, and the length in bytes
> of the packet (packet->length) - to get bitrate, you just need the
> samplerate of the file. To get this, submit the three header packets (at
> the start of the stream) to vorbis_synthesis_headerin() (again, see
> decoder_example). Then vi->rate is the sample rate.
>
> Michael
>
>
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