On Nov 26 2014 23:38, Clemens Ladisch wrote:
Takashi Sakamoto wrote:
On Nov 26 2014 06:52, Clemens Ladisch wrote:
There are several devices that expect to receive MIDI data only in the first eight data blocks of a packet. If the driver restricts the data rate to the allowed rate (as mandated by the specification, but not yet implemented by this driver), this happens naturally. Therefore, there is no reason to ever try to use more data packets with any device.
Signed-off-by: Clemens Ladisch clemens@ladisch.de
sound/firewire/amdtp.c | 10 +++++++--- sound/firewire/amdtp.h | 3 --- sound/firewire/bebob/bebob_stream.c | 7 ------- sound/firewire/fireworks/fireworks_stream.c | 5 ----- 4 files changed, 7 insertions(+), 18 deletions(-)
Can I ask your opinion about applying this patch to devices with non-blocking mode? At least, your comment of this patch is for blocking mode (the fixed number of data blocks in a packet).
This patch does not assume that there is a fixed number of data blocks.
It does not matter whether a stream is (non-)blocking: eight data blocks per packet (i.e., one MIDI byte per MPX-MIDI data channel per packet) is always enough for MIDI. Even at 32 kHz, there are about 4000 packets per seconds in blocking mode. In non-blocking mode, the packets are smaller (so not ecery MPX-MIDI data channels gets sent in every packet), but there are exactly 8000 packets per second, so the overall number of samples (= data blocks) does not change.
I was suspicious of unfairless for 8 MPX-MIDI data streams to transfer MIDI messages in non-blocking mode, because .the MPX-MIDI data stream in the first data block is different per packet.
But this is not matter. At 32.0/44.1/48.0, the number of data blocks in a packet is lesser than 8 therefore all of MPX-MIDI data stream has the same chances to transfer MIDI messages. At 88.2 kHz or higher, the number of data blocks in a packet is bigger than 8 but8 MPX-MIDI data streams has a chance per packet. As a result, All of MPX-MIDI data stream has the same opportunity to transfer MIDI messages.
Reviewed-by: Takashi Sakamoto o-takashi@sakamocchi.jp Tested-by: Takashi Sakamoto o-takashi@sakamocchi.jp
I tested these two patch with below devices. All of them can transmit MIDI messages correctly at any sampling transfer tates.
M-Audio: FIreWire 1814 (snd-bebob) M-Audio: FireWire 410 (snd-bebob) M-Audio: FireWire AudioPhile (snd-bebob) M-Audio: Ozonic (snd-bebob) Yamaha: GO44 (snd-bebob) Yamaha: GO46 (snd-bebob) Echo Audio: AudioFire4 (snd-fireworks) Echo Audio: AudioFirePre8 (snd-fireworks) TC Electronic: Impact Twin (snd-dice)
These two patches solves one of issues which I wrote in my report. 9.5 A lack of throttles for MIDI messages in outgoing stream https://github.com/takaswie/alsa-firewire-report
Thanks
Takashi Sakamoto o-takashi@sakamocchi.jp