mirror of
https://github.com/xemu-project/xemu.git
synced 2025-02-07 04:26:22 +00:00
fd5723b385
Fix a rpos coordination bug between qpa_run_out() and qpa_thread_out(), which shows up as playback noises. qpa_run_out() qpa_thread_out loop N critical section 1 qpa_run_out() qpa_thread_out loop N doing pa_simple_write() qpa_run_out() qpa_thread_out loop N doing pa_simple_write() qpa_thread_out loop N critical section 2 qpa_thread_out loop N+1 critical section 1 qpa_run_out() qpa_thread_out loop N+1 doing pa_simple_write() In the above scheme, "qpa_thread_out loop N+1 critical section 1" will get the same rpos as the one used by "qpa_thread_out loop N critical section 1". So it will be reading dead samples from the old rpos. The rpos can only be updated back to qpa_thread_out when there is a qpa_run_out() run between two qpa_thread_out loops. normal sequence: qpa_thread_out: hw->rpos (X0) => local rpos => pa->rpos (X1) qpa_run_out: pa->rpos (X1) => hw->rpos (X1) qpa_thread_out: hw->rpos (X1) => local rpos => pa->rpos (X2) buggy sequence: qpa_thread_out: hw->rpos (X0) => local rpos => pa->rpos (X1) qpa_thread_out: hw->rpos (X0) => local rpos => pa->rpos (X1') Obviously qpa_run_out() shall be called at least once between any two qpa_thread_out loops (after pa->rpos is set), in order for the new qpa_thread_out loop to see the updated rpos. Setting pa->live to 0 does the trick. The next loop will have to wait for one qpa_run_out() invocation in order to get a non-zero pa->live and proceed. Signed-off-by: malc <av1474@comtv.ru> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Read the documentation in qemu-doc.html. Fabrice Bellard.