CDDA track change messages are displayed when the track is buffered, not when it is played.

[vext01]

mpv version and platform

0.22.0 and master at least.

Reproduction steps

Play a cd, and observe erroneous track change messages.

Expected behavior

Display the track change messages as the listener hears the track change.

Actual behavior

The following output was collected playing track one from a CD:

fremen:edd> mpv cdda://
Playing: cdda://
[cdda] Switched to track 1
 (+) Audio --aid=1 (pcm_s16le)
AO: [sdl] 44100Hz stereo 2ch s16
A: 00:00:19 / 00:37:51 (0%) Cache:  9s+24MB
[cdda] Switched to track 2
A: 00:00:35 / 00:37:51 (1%) Cache:  9s+48MB
[cdda] Switched to track 3
A: 00:01:40 / 00:37:51 (4%) Cache: 10s+72MB
[cdda] Switched to track 4
A: 00:03:00 / 00:37:51 (7%) Cache: 10s+73MB

If you run with --no-cache the messages are printed at the correct time. If you have a cache, the messages are printed as the start sector of a track is buffered, which is confusing.

[vext01]

You can see why this happens by looking at the buffering code in stream_cdda.c:

static int fill_buffer(stream_t *s, char *buffer, int max_len)
{
    cdda_priv *p = (cdda_priv *)s->priv;
    int16_t *buf;
    int i;

    if (max_len < CDIO_CD_FRAMESIZE_RAW)
        return -1;

    if ((p->sector < p->start_sector) || (p->sector > p->end_sector)) {
        return 0;
    }

    buf = paranoia_read(p->cdp, cdparanoia_callback);
    if (!buf)
        return 0;

    p->sector++;
    memcpy(buffer, buf, CDIO_CD_FRAMESIZE_RAW);

    for (i = 0; i < p->cd->tracks; i++) {
        if (p->cd->disc_toc[i].dwStartSector == p->sector - 1) {
            print_track_info(s, i + 1); <---------------- prints the track change message.
            break;
        }
    }

    return CDIO_CD_FRAMESIZE_RAW;
}

[sl1pkn07]

yep. i seen this yesterday when playing/test some CDs

thanks for report it

greetings

[ghost]

That's just how the cache works. It could probably be fixed by exposing the current title as tag or something (emulating it with demux_disc maybe, or reusing the thing for ICY shoutcast metadata), but I don't think anyone has a large enough interest in this.