[Speex-dev] Speex seek with high precision

[Arnau Alemany]

Hello,
This is the code, it's a little crap but only to see if it works. I assume
rate = 16000 and frame_size = 320.

if (this->seek_to != -1)        // SKIP
{
     ogg_int64_t max_units;
    //max_units = speex_seek(fin, this->seek_to, 0, rate);

    int nPages = 0;
    int nPackets = 0;

    // Pone el cursor en la posición inicial del fichero
    fseek(fin, 0, SEEK_SET);

    ogg_int64_t position = (this->seek_to * rate) / 1000;
    ogg_int64_t granulepos;

    do
    {    // Skip pages until the page we want to seek
        granulepos = ogg_page_granulepos(&og);    // previous granulepos
        while (ogg_sync_pageout(&oy, &og) != 1)
        {
            data = ogg_sync_buffer(&oy, 512);
            nb_read = fread(data, 1, 512, fin);
            ogg_sync_wrote(&oy, nb_read);
        }
        nPages++;
    }
    while (ogg_page_granulepos(&og) < position);

    printf("ogg_page_packets: %d\n", ogg_page_packets(&og));

    // Add page to the bitstream
     ogg_stream_pagein(&os, &og);

    printf("ogg_page_packets: %d\n", ogg_page_packets(&og));

    /* Packet counter */
    int res;
    while (true)
    {
        res = ogg_stream_packetout(&os, &op);

        if (res == 1)
            nPackets++;

        if (res == -1)
            printf("out of sync\n");

        if (res == 0)
            break;
    }
    printf("nPackets: %d\n", nPackets);
}

Output is:

ogg_page_granulepos: 164
ogg_page_granulepos: 164
nPackets: 189 // it depends on the page

To do the seeking I change the /*Packet Counter*/ loop by this code and it
almost works well but with a little delay sometimes (always starts decoding
little before):

while (granulepos < position)    // this is almost correct but not always
    {                                             // maybe due to the packet
number difference
        if (ogg_stream_packetout(&os, &op) == 1)
        {
            granulepos += 320;    // granulepos + FRAME_SIZE
            //printf("granulepos: %lld\n", granulepos);
            nPackets++;
        }
    }

Thank you,
Arnau


2009/5/16 Conrad Parker <conrad at metadecks.org>

>
> you mean the number of packets counted is different? Perhaps you are
> feeding pages in differently or something. Can you post your full
> code, including the calls to ogg_stream_pagein()?
>
> Conrad.
>
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