591719 - sa_stream_get_position reports positions in non-sorted order

Status: RESOLVED FIXED

(Core :: Audio/Video, defect)

Description

[Yury Delendik (:yury)]

User-Agent:       Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2.8) Gecko/20100723 Ubuntu/10.04 (lucid) Firefox/3.6.8
Build Identifier: 

The underline libsydney for ALSA (Linux) might reports positions in out of order sequence, which might affect decoder state machine behavior and results of the IDOMMediaElement's currentTime property. See http://mxr.mozilla.org/mozilla-central/source/media/libsydneyaudio/src/sydney_audio_alsa.c#276 : 

  if (state == SND_PCM_STATE_RUNNING) {
    if (snd_pcm_delay(s->output_unit, &delay) != 0) {
      return SA_ERROR_SYSTEM;
    }
  } else {
    delay = 0;
  }
  ...
  *pos = s->bytes_written;
  if (*pos >= snd_pcm_frames_to_bytes(s->output_unit, delay)) {
    *pos -= snd_pcm_frames_to_bytes(s->output_unit, delay);

At the beginning state != SND_PCM_STATE_RUNNING and that makes delay = 0. After audio stream starts playback and the position jumps back quarter of a second.

Reproducible: Sometimes

Comment 1

[Yury Delendik (:yury)]

Attachment: Stores last good position to maintain the order

Comment 2

[Matthew Gregan [:kinetik]]

Comment on attachment 470246 [details] [diff] [review]
Stores last good position to maintain the order

Thanks for the patch!

Comment 3

[Chris Pearce [:cpearce (Not reading bugmail)]]

http://hg.mozilla.org/mozilla-central/rev/48dec3f80d50