• Takashi Sakamoto's avatar
    ALSA: firewire-tascam: perform sequence replay for media clock recovery · a9dd8a61
    Takashi Sakamoto authored
    This commit takes ALSA firewire-tascam driver to perform sequence replay
    for media clock recovery.
    
    The protocol specific to Tascam FireWire series is not compliant to
    IEC 61883-1/6 in terms of syt field of CIP. The protocol doesn't use
    presentation time in received CIP for playback timing. The sequence of
    the number of data blocks per packet is important for media clock
    recovery.
    
    Although the devices in Tascam FireWire series transfer packets
    regardless of receiving packets, the tx packets includes no events
    in the beginning of streaming. It takes so long to multiplex any event
    into the packet after receiving the sequence of packets. As long as I
    experienced, it takes several thousands of isochronous cycle. Furthermore,
    just after changing sampling transmission frequency, it stops multiplexing
    event at once, then starts multiplexing again.
    
    The sequence replay is tested with below models:
     * FW-1884
     * FW-1804
     * FW-1082
    Signed-off-by: default avatarTakashi Sakamoto <o-takashi@sakamocchi.jp>
    Link: https://lore.kernel.org/r/20210531025103.17880-6-o-takashi@sakamocchi.jpSigned-off-by: default avatarTakashi Iwai <tiwai@suse.de>
    a9dd8a61
tascam.h 6.2 KB