Hi,
Current implementation of ALSA IEC 61883-1/6 packet streaming engine doesn't check whether received packets are exactly per isochronous cycle. This is required to process packets transferred from OXFW970-based devices and devices in RME Fireface series. However, the packet sequence with skipped cycle is inconvenient for media clock recovery.
This patchset takes the engine to check cycle continuity at processing packets, including code refactoring. For RME Fireface series, the skipped cycle is handled as receiving an empty packet. For OXFW970-based devices, the skipped cycles are acceptable but media clock recovery is hard.
Takashi Sakamoto (8): ALSA: firewire-lib: code refactoring to refer the same frame count per period in domain structure ALSA: firewire-lib: handle the case that empty isochronous packet payload for CIP ALSA: firewire-lib: code refactoring for sequence descriptor' ALSA: firewire-lib: code refactoring for helper function to compute OHCI 1394 cycle ALSA: firewire-lib: code refactoring for parser of IR context header ALSA: firewire-lib: code refactoring for check of CIP header about payload size ALSA: firewire-lib: check cycle continuity ALSA: firewire-lib: insert descriptor for skipped cycle
sound/firewire/amdtp-stream.c | 172 ++++++++++++++++++++++------------ sound/firewire/amdtp-stream.h | 10 +- 2 files changed, 119 insertions(+), 63 deletions(-)