[gst-devel] Audiosink problems for ARM

Joyious He joyious at 163.com
Fri Sep 28 13:54:04 CEST 2007

  Hi all,
Here I have some questions for gstreamer audiosink:
I'm using the osssink on my arm board, and no sound came out
command:gst-launch -v audiotestsrc ! audioconvert ! audioresample ! osssink
I checked the source code and the debug info, then find the ringbuffer writer is some slower than the reader.
see the debug info:
0:00:08.656034000 1491 0x3e030 DEBUG baseaudiosink gstbaseaudiosink.c:848:gst_base_audio_sink_render:<osssink0> align with prev sample, 25 < 24000
0:00:08.656789000 1491 0x3e030 DEBUG baseaudiosink gstbaseaudiosink.c:880:gst_base_audio_sink_render:<osssink0> rendering at 78822 1024/1024
0:00:08.657666000 1491 0x3e030 DEBUG ringbuffer gstringbuffer.c:1362:gst_ring_buffer_commit_full: pointer at 19, write to 4-26572, diff -15, segtotal 3, segsize 32768
0:00:08.658613000 1491 0x3e030 DEBUG ringbuffer gstringbuffer.c:1394:gst_ring_buffer_commit_full:<audiosinkringbuffer0> write @0x4069e008 seg 1, sps 16384, off 26572, avail 2048
0:00:08.659525000 1491 0x3e030 DEBUG ringbuffer gstringbuffer.c:1398:gst_ring_buffer_commit_full: copy 2048 bytes
0:00:08.660592000 1491 0x3e030 DEBUG baseaudiosink gstbaseaudiosink.c:895:gst_base_audio_sink_render:<osssink0> wrote 1024 of 1024
0:00:08.661479000 1491 0x3e030 DEBUG baseaudiosink gstbaseaudiosink.c:911:gst_base_audio_sink_render:<osssink0> next sample expected at 79846
0:00:08.738888000 1491 0x3e030 DEBUG baseaudiosink gstbaseaudiosink.c:669:gst_base_audio_sink_render:<osssink0> time 0:00:01.664000000, offset 79872, start 0:00:00.000000000, samples 1024
0:00:08.740013000 1491 0x3e030 DEBUG baseaudiosink gstbaseaudiosink.c:738:gst_base_audio_sink_render:<osssink0> running: start 0:00:01.664000000 - stop 0:00:01.685333333
0:00:08.741028000 1491 0x3e030 DEBUG baseaudiosink gstbaseaudiosink.c:743:gst_base_audio_sink_render:<osssink0> base_time 0:00:00.000000000
0:00:08.741940000 1491 0x3e030 DEBUG baseaudiosink gstbaseaudiosink.c:752:gst_base_audio_sink_render:<osssink0> compensating for latency 0:00:00.000000000
since the diff < 0,so the data copying is skipped;
I change this behavior to copying the data anyway:
 /* segment too far ahead, writer too slow, we need to drop, hopefully UNLIKELY */
 if (G_UNLIKELY (diff < 0)) {
 /* we need to drop one segment at a time, pretend we wrote a
 * segment. */
 // skip = TRUE;
 skip = FALSE; //test
Now the sound comes out,but it's not continous.
So I wonder the reason, is my hardware or the ringbuffer thread read the data faster than my ringbuffer writer ? is this gst_ring_buffer_prepare_read() keep running without waiting the buffer writer to input some datas ?
As I also saw the design-audiosinks.txt, it says:
 A write operation to the ringbuffer will put new samples in the ringbuffer.
 If there is not enough space in the ringbuffer, the write operation will
 block. The playback of the buffer never stops, even if the buffer is
 empty. When the buffer is empty, silence is played by the device.
Now how can I solve this problem ? To make the playback wait for the data writer ? Or to make the data write fast enough ? BTW, the Gstreamer is taking up almost 99% CPU of my arm board.
Hope you can help me to answer these questions.
Many Thanks,
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