https://www.alsa-project.org/main/api.php?action=feedcontributions&feedformat=atom&user=TakaswieAlsaProject - User contributions [en]2026-04-26T16:07:22ZUser contributionsMediaWiki 1.39.0https://www.alsa-project.org/main/index.php?title=User:Takaswie&diff=6700User:Takaswie2014-02-21T03:18:52Z<p>Takaswie: </p>
<hr />
<div>Simple memo about driver for Firewire devices<br />
<br />
1.Status of this document<br />
<br />
My memo for developing.<br />
<br />
2.Basic Specifications<br />
- 'IEEE1394' defines 'Phy layer', 'Link layer', 'Transaction layer' and 'Serial Bus Management'.<br />
- 'IEEE1212' defines 'Control ans Status Registers (CSR)', 'Configuration ROM' and 'Transaction set'.<br />
- 'OHCI1394' defined the design of IEEE1394 host controller and its register.<br />
- 'IEC 61883-1' defines 'Common Isochronous Packet (CIP)', 'Isochronous data flow management', 'Connection Management Procedure (CMP)', 'Function Control Protocol (FCP)'.<br />
- 'IEC 61883-6' defines the way to packetize 'Common Isochronous Packet' for 'Audio and Music'. This is so-called 'AMDTP'.<br />
- 'MMA/AMEI RP-027' is a recommendation for 'MIDI conformant data' channel of 'AMDTP'.<br />
- '1394TA' is an associates of industory.<br />
- 'AV/C' is many series of specification defined by '1394TA'.<br />
<br />
3.Firewire Sound Devices<br />
- They typically have:<br />
- a chipset for 'IEEE1394 Phy layer and Link layer'<br />
- a firmware for 'Transaction layer', 'Serial Bus Management' and 'IEC 61883-1/6'<br />
- a chipset for signal processing<br />
- a chipset for D/A or A/D convertion<br />
<br />
4.Firewire Sound Drivers<br />
- Firewire Sound Drivers Use IEEE1394 host controller to communicate to Firewire Sound Devices<br />
- In Linux, driver of host controller is developed at ieee1394.wiki.kernel.org. This driver has a nick name, 'Juju'. This driver exports some kernel APIs.<br />
- ALSA Firewire Sound Drivers use the kernel APIs.<br />
- 'snd-firewire-lib' exports helper functions for ALSA Firewire Sound Drivers.<br />
<br />
5.What to do inner Firewire Sound Drivers<br />
- Register/unregister myself as module for Linux<br />
- React bus events with Juju<br />
- Register/unregister cards for ALSA Core<br />
- Add interfaces for ALSA components<br />
- Handle Input/Output to/from ALSA applications<br />
- Send/Receive transactions to/from Firewire Sound Devices<br />
- Send/Receive packets to/from Firewire Sound Devices<br />
- Parse/Compose data for Firewire Sound Devices<br />
<br />
6.Connections<br />
- See IEC 61883-1.<br />
- This is for Firewire Sound Devices compliant to IEC 61883-1.<br />
- They manage isochronous resource with 'Connection'.<br />
- This 'Connection' is expressed as a value of 'Plug Control Register'.<br />
- The drivers send/receive transactions to handle 'Plug Control Register'.<br />
- The way to handle 'Connection' is defined in IEC 61883-1.<br />
<br />
7.Packets<br />
- See IEC 61883-1.<br />
- 'Isochronous Packet' has its own header. Its payload has a 'Common Isochronous Packet'.<br />
- 'Common Isochronous Packet' have its own header. Its payload has some data blocks.<br />
- 'AMDTP' uses 'Common Isochronous Packet header with SYT field'.<br />
- In 'AMDTP', data block consists of some data channels.<br />
- For Firewire Sound Devices, the data channel is generally used for PCM samples and MIDI messages.<br />
- 'PCM samples' and 'MIDI messages' can be transferred in the same 'AMDTP' packet.<br />
<br />
8.Presentation Timestamp<br />
- See IEC 61883-1.<br />
- This is in a 'SYT' field in 'Common Isochronous Packet header with SYT field'.<br />
- This field is 16 bit. This field cannot indicate an actual time.<br />
- The value of this field is '0xffff' if the packet has no 'presentation timestamp'.<br />
- The devices can be synchronized with the value of this field.<br />
- Firewire Sound Drivers need to calcurate the value of this field in 'out-stream'.<br />
- Then Firewire Sound Drivers should use the value of this field in 'in-stream' for 'out-stream'.<br />
<br />
9.AMDTP and PCM samples<br />
- See IEC 61883-6.<br />
- The value of 'FDF' in 'Common Isochronous Packet' header includes 'SFC' field for 'sampling rate'.<br />
- 'Common Isochronous Packet' includes some 'event' in its data block.<br />
- The 'event' means 'data in the same timestamp'. So one 'event' includes a set of PCM channels (= one frame).<br />
- There are two ways to decide the number of 'events' in an 'Common Isochronous Packet', 'non-blocking' and 'blocking'.<br />
- In 'non-blocking' mode:<br />
- In each 'Common Isochronous Packet', the number of 'event' is different.<br />
- All of 'Common Isochronous Packet' has PCM samples.<br />
- The value of 'SYT' field is for a certain 'event' in the 'Common Isochronous Packet'.<br />
- In 'blocking' mode:<br />
- In each 'Common Isochronous Packet', the number of 'event' is the same.<br />
- Some 'Common Isochronous Packet' has no PCM samples (empty packet or packet with NODATA flag).<br />
- The value of 'SYT' field is for the first 'event' in the 'Common Isochronous Packet'.<br />
- In both modes, the total number of 'events' with PCM samples are the same as sampling rate.<br />
- Most Firewire Sound Devies use 'blocking mode'.<br />
<br />
10.MIDI Conformant Data Channel<br />
- See IEC 61883-6 and MMA/AMEI RP-027.<br />
- 'MIDI Conformant Data Channel' is for transfer of MIDI messages.<br />
- Each 'MIDI Conformant Data Channel' includes 8 'MPX-MIDI Data Stream'.<br />
- Each 'MPX-MIDI Data Stream' includes one data stream from/to MIDI ports.<br />
- 'MIDI1.0-1x-SPEED' mode is major.<br />
- 'MIDI1.0-2x/3x-SPEED' mode are described with 'negotiation procedure' and 'encapsulation details' but there is no specifications to define them.<br />
<br />
11.Function Control Protocol<br />
- See IEC 61883-1.<br />
- 'Function Control Protocol' is an application of 'Asynchronous Transaction' in IEEE1394.<br />
- 'Function Control Protocol' is done by command/response.<br />
- Command is sent to '0xffff f000 0b00'<br />
- Response is sent to '0xffff f000 0d00'<br />
- To receive response from device, drivers need to listen this address (so-called allocation).<br />
<br />
12.AV/C commands<br />
- 'AV/C commands' is an application of 'Function Cotrol Protocol'.<br />
- The maximum size of command is 512 bytes.<br />
- There are much variations, vendor-specific extensions.<br />
- Basically, see 'AV/C Digital Interface Command Set General Specification Version 4.2 (Sept 2004, 1394TA)'.<br />
- For Audio Subunit, see 'AV/C Audio Subunit Specification 1.0 (Oct 2000, 1394TA)'.<br />
- For Music Subunit, see 'AV/C Music Subunit Specification 1.0 (I don't have)'.<br />
- For Stream Format, see 'AV/C Stream Format Information Specification 1.0 (I don't have)'<br />
- For Descriptor Mechanism, see 'Enhancements to the AV/C General Specification 3.0 Version 1.1 (Oct 2000, 1394TA)'.<br />
<br />
13.Sampling Clock Source<br />
- This is device-dependent issue.<br />
- Usually Firewire Sound Devices use internal clock.<br />
- But some devices can switch its source of sampling clock. <br />
- There is Coaxial, Optical and XLR interface for this purpose.<br />
- And there is 'Synchronization Stream'. In this stream, the value of 'SYT' field can be used for sampling clock.<br />
- When source of clock is given by external, available sampling rate is limited at current one.<br />
<br />
14.Quirks<br />
- Fireworks:<br />
- 1.Fireworks transmits packets with both TAG0 and TAG1. In IEC 61883-1, each common isochronous packet (CIP) has 'tag' field in its packet header. The value is generally 0x01 ('CIP header is included' = TAG1). But Fireworks in 'IEC 61883 compliant mode' transmits 'no data' packet with 0x00 ('No CIP header is included' = TAG0) but actually the packet includes CIP structure. To handle 'presentation timestamp' for duplex streams synchronization, this packets must be handled.<br />
<br />
- 2.Fireworks transmits 'no data' packet out of specification. Fireworks transmits 'no data' packet with 'NO-DATA' FDF and no dummy data. It includes CIP headers only. In IEC 61883-6, 'no data' packet is generated by two ways. One is empty CIP packet defined in IEC 61883-1. Another is 'special non-empty packet' defined in IEC 61883-6. Fireworks uses strange combination of them.<br />
<br />
- 3.Fireworks can handle MIDI messages in the first 8 data blocks of out-packet, Fireworks ignores MIDI messages in other data blocks.<br />
<br />
- 4.AudioFirePre8 transmits packets with wrong data block size. One of Fireworks device, AudioFirePre8, always reports 8 data block size in transmitted packets and increments the data block counter by 8. But this is not actual value.<br />
<br />
- 5.Fireworks transmits packets with a bit disorder. See:<br />
<pre><br />
Index Payload CIP header 1CIP header 2<br />
023 210 3F1100F8 900478E9<br />
024 002 3F1100F8 90FFFFFF<br />
025 210 3F110000 900490E9<br />
026 210 3F110008 9004A4E9<br />
027 210 3F110010 9004B8E9<br />
028 002 3F110010 90FFFFFF<br />
029 210 3F110020 9004E4E8 <-<br />
030 210 3F110018 9004D0E8 <-<br />
031 210 3F110028 9004F8E8<br />
032 002 3F110028 90FFFFFF<br />
033 210 3F110030 900410E8<br />
034 210 3F110038 900424E8<br />
035 210 3F110040 900438E8<br />
036 002 3F110040 90FFFFFF<br />
037 210 3F110050 900464E8 <-<br />
038 210 3F110048 900450E8 <-<br />
039 210 3F110058 900478E8<br />
040 002 3F110058 90FFFFFF<br />
041 210 3F110068 9004A4E8 <-<br />
042 210 3F110060 900490E8 <-<br />
043 210 3F110070 9004B8E8<br />
044 002 3F110070 90FFFFFF<br />
045 210 3F110080 9004E4E7 <-<br />
046 210 3F110078 9004D0E8 <-<br />
</pre><br />
<br />
- BeBoB<br />
- BeBoB has its own AV/C extension command<br />
<br />
- OXFW970/971<br />
- OXFW970/971 transmit packets with invalid value of 'SYT' field. See:<br />
<pre><br />
When driver gives no out-stream:<br />
Index Payload CIP_Header_0 CIP_Header_1<br />
38 14 00020092 900103D1<br />
39 12 00020098 900102FF<br />
40 12 0002009D 9001027F<br />
41 14 000200A2 90010396<br />
42 14 000200A8 900102E8<br />
43 12 000200AE 90010219<br />
44 14 000200B3 90010331<br />
45 12 000200B9 9001025F<br />
46 14 000200BE 90010376<br />
47 12 000200C4 900102A1<br />
00 12 000200C9 9001023E<br />
01 14 000200CE 90010358<br />
02 12 000200D4 90010289<br />
03 16 000200D9 900103A3<br />
04 12 000200E0 900102DD<br />
05 14 000200E5 900103F1<br />
06 12 000200EB 90010335<br />
07 12 000200F0 90010263<br />
08 14 000200F5 9001037C<br />
09 12 000200FB 900102AE<br />
</pre><br />
<br />
<pre><br />
When driver gives out-stream:<br />
Index Payload CIP_Header_0 CIP_Header_1<br />
38 12 000200BD 900104A8<br />
39 14 000200C2 900104A8<br />
40 12 000200C8 900104AC<br />
41 14 000200CD 900104A9<br />
42 12 000200D3 900104B1<br />
43 14 000200D8 900104A8<br />
44 12 000200DE 900104AA<br />
45 14 000200E3 900104A9<br />
46 14 000200E9 900104AE<br />
47 12 000200EF 900104A8<br />
00 14 000200F4 900104AD<br />
01 12 000200FA 900104A7<br />
02 14 000200FF 900104A9<br />
03 12 00020005 900104A9<br />
04 14 0002000A 900104B1<br />
05 12 00020010 900104AA<br />
06 14 00020015 900104AD<br />
07 12 0002001B 900104A7<br />
08 14 00020020 900104AC<br />
09 12 00020026 900104A7<br />
</pre><br />
<br />
End</div>Takaswiehttps://www.alsa-project.org/main/index.php?title=User:Takaswie&diff=6696User:Takaswie2014-01-30T06:00:57Z<p>Takaswie: </p>
<hr />
<div>Simple memo about driver for Firewire devices<br />
<br />
1.Status of this document<br />
<br />
My memo for developing.<br />
<br />
2.Basic Specifications<br />
- 'IEEE1394' defines 'Phy layer', 'Link layer', 'Transaction layer' and 'Serial Bus Management'.<br />
- 'OHCI1394' defined the design of IEEE1394 host controller and its register.<br />
- 'IEC 61883-1' defines 'Common Isochronous Packet (CIP)', 'Isochronous data flow management', 'Connection Management Procedure (CMP)', 'Function Control Protocol (FCP)'.<br />
- 'IEC 61883-6' defines the way to packetize 'Common Isochronous Packet' for 'Audio and Music'. This is so-called 'AMDTP'.<br />
- 'MMA/AMEI RP-027' is a recommendation for 'MIDI conformant data' channel of 'AMDTP'.<br />
- '1394TA' is an associates of industory.<br />
- 'AV/C' is many series of specification defined by '1394TA'.<br />
<br />
3.Firewire Sound Devices<br />
- They typically have:<br />
- a chipset for 'IEEE1394 Phy layer and Link layer'<br />
- a firmware for 'Transaction layer', 'Serial Bus Management' and 'IEC 61883-1/6'<br />
- a chipset for signal processing<br />
- a chipset for D/A or A/D convertion<br />
<br />
4.Firewire Sound Drivers<br />
- Firewire Sound Drivers Use IEEE1394 host controller to communicate to Firewire Sound Devices<br />
- In Linux, driver of host controller is developed at ieee1394.wiki.kernel.org. This driver has a nick name, 'Juju'. This driver exports some kernel APIs.<br />
- ALSA Firewire Sound Drivers use the kernel APIs.<br />
- 'snd-firewire-lib' exports helper functions for ALSA Firewire Sound Drivers.<br />
<br />
5.What to do inner Firewire Sound Drivers<br />
- Register/unregister myself as module for Linux<br />
- React bus events for Juju<br />
- Register/unregister cards for ALSA Core<br />
- Add interfaces for ALSA component<br />
- Handle Input/Output to/from ALSA applications<br />
- Send/Receive transactions to/from Firewire Sound Devices<br />
- Send/Receive packets to/from Firewire Sound Devices<br />
- Parse/Compose data for Firewire Sound Devices<br />
<br />
6.Connections<br />
- See IEC 61883-1.<br />
- This is for Firewire Sound Devices compliant to IEC 61883-1.<br />
- They manage isochronous resource with 'Connection'.<br />
- This 'Connection' is expressed as a value of 'Plug Control Register'.<br />
- The way to handle 'Connection' is defined in IEC 61883-1.<br />
<br />
7.Packets<br />
- See IEC 61883-1.<br />
- 'Isochronous Packet' has its own header. In its payload, some 'Common Isochronous Packet'.<br />
- 'Common Isochronous Packet' have its own header. In its payload, some data channels.<br />
- 'AMDTP' uses 'Common Isochronous Packet header with SYT field'.<br />
- In 'AMDTP', 'Common Isochronous Packet' have some data channels.<br />
- For Firewire Sound Devices, the data channel is mainly used for PCM samples and MIDI messages.<br />
- 'PCM samples' and 'MIDI messages' can be transferred in the same 'AMDTP' packet.<br />
<br />
8.Presentation Timestamp<br />
- See IEC 61883-1.<br />
- This is in a 'SYT' field in 'Common Isochronous Packet header with SYT field'.<br />
- This field is 16 bit. This field cannot indicate an actual time.<br />
- The value of this field is '0xffff' if the packet has no 'presentation timestap'.<br />
- The devices can be synchronized with the value of this field.<br />
- Firewire Sound Drivers need to calculare the value of this field in 'out-stream'.<br />
- Then Firewire Sound Drivers should use the value of this field in 'in-stream' for 'out-stream'.<br />
<br />
9.AMDTP and PCM samples<br />
- See IEC 61883-6.<br />
- The value of 'FDF' in 'Common Isochronous Packet' header includes 'SFC' field for 'sampling rate'.<br />
- 'Common Isochronous Packet' includes some 'event'.<br />
- The 'event' means 'data in the same timestamp'. So one 'event' includes a set of PCM channels (= one frame).<br />
- There are two ways to decide the number of 'events' in an 'Common Isochronous Packet', 'non-blocking' and 'blocking'.<br />
- In 'non-blocking' mode:<br />
- In each 'Common Isochronous Packet', the number of 'event' is different.<br />
- All of 'Common Isochronous Packet' has PCM samples.<br />
- The value of 'SYT' field is for a certain 'event' in the 'Common Isochronous Packet'.<br />
- In 'blocking' mode:<br />
- In each 'Common Isochronous Packet', the number of 'event' is the same.<br />
- Some 'Common Isochronous Packet' has no PCM samples (empty packet or packet with NODATA flag).<br />
- The value of 'SYT' field is for the first 'event' in the 'Common Isochronous Packet'.<br />
- In both modes, the total number of 'events' with PCM samples are the same as sampling rate.<br />
- Most Firewire Sound Devies use 'blocking mode'.<br />
<br />
10.MIDI Conformant Data Channel<br />
- See IEC 61883-6 and MMA/AMEI RP-027.<br />
- 'MIDI Conformant Data Channel' is for transfer MIDI messages.<br />
- Each 'MIDI Conformant Data Channel' includes 8 'MPX-MIDI Data Stream'.<br />
- Each 'MPX-MIDI Data Stream' includes one data stream from/to MIDI ports.<br />
- 'MIDI1.0-1x-SPEED' mode is major.<br />
- 'MIDI1.0-2x/3x-SPEED' mode are described with 'negotiation procedure' and 'encapsulation details' but there is no specifications to define them.<br />
<br />
11.Function Control Protocol<br />
- See IEC 61883-6.<br />
- 'Function Control Protocol' is an application of 'Asynchronous Transaction' in IEEE1394.<br />
- 'Function Control Protocol' is done by command/response.<br />
- Command is sent to '0xffff f000 0b00'<br />
- Response is sent to '0xffff f000 0d00'<br />
- To receive response from device, drivers need to listen this address (so-called allocation).<br />
<br />
12.AV/C commands<br />
- 'AV/C commands' is an application of 'Function Cotrol Protocol'.<br />
- The maximum size of command is 512 bytes.<br />
- There are much variations, vendor-specific extensions.<br />
- Basically, see 'AV/C Digital Interface Command Set General Specification Version 4.2 (Sept 2004, 1394TA)'.<br />
- For Audio Subunit, see 'AV/C Audio Subunit Specification 1.0 (Oct 2000, 1394TA)'.<br />
- For Music Subunit, see 'AV/C Music Subunit Specification 1.0 (I don't have)'.<br />
- For Stream Format, see 'AV/C Stream Format Information Specification 1.0 (I don't have)'<br />
- For Descriptor Mechanism, see 'Enhancements to the AV/C General Specification 3.0 Version 1.1 (Oct 2000, 1394TA)'.<br />
<br />
13.Sampling Clock Synchronization<br />
- This is device-dependent issue.<br />
- Usually Firewire Sound Devices use internal clock.<br />
- But some devices can switch its source of sampling clock. <br />
- There is Coaxial, Optical and XLR interface for this purpose.<br />
- And there is 'Synchronization Stream'. In this stream, the value of 'SYT' field can be used for sampling clock.<br />
- When source of clock is given by external, available sampling rate is limited at current one.<br />
<br />
14.Quirks<br />
- Fireworks:<br />
- 1.Fireworks transmits packets with both TAG0 and TAG1. In IEC 61883-1, each common isochronous packet (CIP) has 'tag' field in its packet header. The value is generally 0x01 ('CIP header is included' = TAG1). But Fireworks in 'IEC 61883 compliant mode' transmits 'no data' packet with 0x00 ('No CIP header is included' = TAG0) but actually the packet includes CIP structure. To handle 'presentation timestamp' for duplex streams synchronization, this packets must be handled.<br />
<br />
- 2.Fireworks transmits 'no data' packet out of specification. Fireworks transmits 'no data' packet with 'NO-DATA' FDF and no dummy data. It includes CIP headers only. In IEC 61883-6, 'no data' packet is generated by two ways. One is empty CIP packet defined in IEC 61883-1. Another is 'special non-empty packet' defined in IEC 61883-6. Fireworks uses strange combination of them.<br />
<br />
- 3.Fireworks can handle MIDI messages in the first 8 data blocks of out-packet, Fireworks ignores MIDI messages in other data blocks.<br />
<br />
- 4.AudioFirePre8 transmits packets with wrong data block size. One of Fireworks device, AudioFirePre8, always reports 8 data block size in transmitted packets and increments the data block counter by 8. But this is not actual value.<br />
<br />
- 5.Fireworks transmits packets with a bit disorder. See:<br />
<pre><br />
Index Payload CIP header 1CIP header 2<br />
023 210 3F1100F8 900478E9<br />
024 002 3F1100F8 90FFFFFF<br />
025 210 3F110000 900490E9<br />
026 210 3F110008 9004A4E9<br />
027 210 3F110010 9004B8E9<br />
028 002 3F110010 90FFFFFF<br />
029 210 3F110020 9004E4E8 <-<br />
030 210 3F110018 9004D0E8 <-<br />
031 210 3F110028 9004F8E8<br />
032 002 3F110028 90FFFFFF<br />
033 210 3F110030 900410E8<br />
034 210 3F110038 900424E8<br />
035 210 3F110040 900438E8<br />
036 002 3F110040 90FFFFFF<br />
037 210 3F110050 900464E8 <-<br />
038 210 3F110048 900450E8 <-<br />
039 210 3F110058 900478E8<br />
040 002 3F110058 90FFFFFF<br />
041 210 3F110068 9004A4E8 <-<br />
042 210 3F110060 900490E8 <-<br />
043 210 3F110070 9004B8E8<br />
044 002 3F110070 90FFFFFF<br />
045 210 3F110080 9004E4E7 <-<br />
046 210 3F110078 9004D0E8 <-<br />
</pre><br />
<br />
- BeBoB<br />
- BeBoB has its own AV/C extension command<br />
<br />
- OXFW970/971<br />
- OXFW970/971 transmit packets with invalid value of 'SYT' field. See:<br />
<pre><br />
When driver gives no out-stream:<br />
Index Payload CIP_Header_0 CIP_Header_1<br />
38 14 00020092 900103D1<br />
39 12 00020098 900102FF<br />
40 12 0002009D 9001027F<br />
41 14 000200A2 90010396<br />
42 14 000200A8 900102E8<br />
43 12 000200AE 90010219<br />
44 14 000200B3 90010331<br />
45 12 000200B9 9001025F<br />
46 14 000200BE 90010376<br />
47 12 000200C4 900102A1<br />
00 12 000200C9 9001023E<br />
01 14 000200CE 90010358<br />
02 12 000200D4 90010289<br />
03 16 000200D9 900103A3<br />
04 12 000200E0 900102DD<br />
05 14 000200E5 900103F1<br />
06 12 000200EB 90010335<br />
07 12 000200F0 90010263<br />
08 14 000200F5 9001037C<br />
09 12 000200FB 900102AE<br />
</pre><br />
<br />
<pre><br />
When driver gives out-stream:<br />
Index Payload CIP_Header_0 CIP_Header_1<br />
38 12 000200BD 900104A8<br />
39 14 000200C2 900104A8<br />
40 12 000200C8 900104AC<br />
41 14 000200CD 900104A9<br />
42 12 000200D3 900104B1<br />
43 14 000200D8 900104A8<br />
44 12 000200DE 900104AA<br />
45 14 000200E3 900104A9<br />
46 14 000200E9 900104AE<br />
47 12 000200EF 900104A8<br />
00 14 000200F4 900104AD<br />
01 12 000200FA 900104A7<br />
02 14 000200FF 900104A9<br />
03 12 00020005 900104A9<br />
04 14 0002000A 900104B1<br />
05 12 00020010 900104AA<br />
06 14 00020015 900104AD<br />
07 12 0002001B 900104A7<br />
08 14 00020020 900104AC<br />
09 12 00020026 900104A7<br />
</pre><br />
<br />
End</div>Takaswiehttps://www.alsa-project.org/main/index.php?title=User:Takaswie&diff=6695User:Takaswie2014-01-30T06:00:16Z<p>Takaswie: Created page with "Simple memo about driver for Firewire devices 1.Status of this document My memo for developing. 2.Basic Specifications - 'IEEE1394' defines 'Phy layer', 'Link layer', 'Tran..."</p>
<hr />
<div>Simple memo about driver for Firewire devices<br />
<br />
1.Status of this document<br />
My memo for developing.<br />
<br />
2.Basic Specifications<br />
- 'IEEE1394' defines 'Phy layer', 'Link layer', 'Transaction layer' and 'Serial Bus Management'.<br />
- 'OHCI1394' defined the design of IEEE1394 host controller and its register.<br />
- 'IEC 61883-1' defines 'Common Isochronous Packet (CIP)', 'Isochronous data flow management', 'Connection Management Procedure (CMP)', 'Function Control Protocol (FCP)'.<br />
- 'IEC 61883-6' defines the way to packetize 'Common Isochronous Packet' for 'Audio and Music'. This is so-called 'AMDTP'.<br />
- 'MMA/AMEI RP-027' is a recommendation for 'MIDI conformant data' channel of 'AMDTP'.<br />
- '1394TA' is an associates of industory.<br />
- 'AV/C' is many series of specification defined by '1394TA'.<br />
<br />
3.Firewire Sound Devices<br />
- They typically have:<br />
- a chipset for 'IEEE1394 Phy layer and Link layer'<br />
- a firmware for 'Transaction layer', 'Serial Bus Management' and 'IEC 61883-1/6'<br />
- a chipset for signal processing<br />
- a chipset for D/A or A/D convertion<br />
<br />
4.Firewire Sound Drivers<br />
- Firewire Sound Drivers Use IEEE1394 host controller to communicate to Firewire Sound Devices<br />
- In Linux, driver of host controller is developed at ieee1394.wiki.kernel.org. This driver has a nick name, 'Juju'. This driver exports some kernel APIs.<br />
- ALSA Firewire Sound Drivers use the kernel APIs.<br />
- 'snd-firewire-lib' exports helper functions for ALSA Firewire Sound Drivers.<br />
<br />
5.What to do inner Firewire Sound Drivers<br />
- Register/unregister myself as module for Linux<br />
- React bus events for Juju<br />
- Register/unregister cards for ALSA Core<br />
- Add interfaces for ALSA component<br />
- Handle Input/Output to/from ALSA applications<br />
- Send/Receive transactions to/from Firewire Sound Devices<br />
- Send/Receive packets to/from Firewire Sound Devices<br />
- Parse/Compose data for Firewire Sound Devices<br />
<br />
6.Connections<br />
- See IEC 61883-1.<br />
- This is for Firewire Sound Devices compliant to IEC 61883-1.<br />
- They manage isochronous resource with 'Connection'.<br />
- This 'Connection' is expressed as a value of 'Plug Control Register'.<br />
- The way to handle 'Connection' is defined in IEC 61883-1.<br />
<br />
7.Packets<br />
- See IEC 61883-1.<br />
- 'Isochronous Packet' has its own header. In its payload, some 'Common Isochronous Packet'.<br />
- 'Common Isochronous Packet' have its own header. In its payload, some data channels.<br />
- 'AMDTP' uses 'Common Isochronous Packet header with SYT field'.<br />
- In 'AMDTP', 'Common Isochronous Packet' have some data channels.<br />
- For Firewire Sound Devices, the data channel is mainly used for PCM samples and MIDI messages.<br />
- 'PCM samples' and 'MIDI messages' can be transferred in the same 'AMDTP' packet.<br />
<br />
8.Presentation Timestamp<br />
- See IEC 61883-1.<br />
- This is in a 'SYT' field in 'Common Isochronous Packet header with SYT field'.<br />
- This field is 16 bit. This field cannot indicate an actual time.<br />
- The value of this field is '0xffff' if the packet has no 'presentation timestap'.<br />
- The devices can be synchronized with the value of this field.<br />
- Firewire Sound Drivers need to calculare the value of this field in 'out-stream'.<br />
- Then Firewire Sound Drivers should use the value of this field in 'in-stream' for 'out-stream'.<br />
<br />
9.AMDTP and PCM samples<br />
- See IEC 61883-6.<br />
- The value of 'FDF' in 'Common Isochronous Packet' header includes 'SFC' field for 'sampling rate'.<br />
- 'Common Isochronous Packet' includes some 'event'.<br />
- The 'event' means 'data in the same timestamp'. So one 'event' includes a set of PCM channels (= one frame).<br />
- There are two ways to decide the number of 'events' in an 'Common Isochronous Packet', 'non-blocking' and 'blocking'.<br />
- In 'non-blocking' mode:<br />
- In each 'Common Isochronous Packet', the number of 'event' is different.<br />
- All of 'Common Isochronous Packet' has PCM samples.<br />
- The value of 'SYT' field is for a certain 'event' in the 'Common Isochronous Packet'.<br />
- In 'blocking' mode:<br />
- In each 'Common Isochronous Packet', the number of 'event' is the same.<br />
- Some 'Common Isochronous Packet' has no PCM samples (empty packet or packet with NODATA flag).<br />
- The value of 'SYT' field is for the first 'event' in the 'Common Isochronous Packet'.<br />
- In both modes, the total number of 'events' with PCM samples are the same as sampling rate.<br />
- Most Firewire Sound Devies use 'blocking mode'.<br />
<br />
10.MIDI Conformant Data Channel<br />
- See IEC 61883-6 and MMA/AMEI RP-027.<br />
- 'MIDI Conformant Data Channel' is for transfer MIDI messages.<br />
- Each 'MIDI Conformant Data Channel' includes 8 'MPX-MIDI Data Stream'.<br />
- Each 'MPX-MIDI Data Stream' includes one data stream from/to MIDI ports.<br />
- 'MIDI1.0-1x-SPEED' mode is major.<br />
- 'MIDI1.0-2x/3x-SPEED' mode are described with 'negotiation procedure' and 'encapsulation details' but there is no specifications to define them.<br />
<br />
11.Function Control Protocol<br />
- See IEC 61883-6.<br />
- 'Function Control Protocol' is an application of 'Asynchronous Transaction' in IEEE1394.<br />
- 'Function Control Protocol' is done by command/response.<br />
- Command is sent to '0xffff f000 0b00'<br />
- Response is sent to '0xffff f000 0d00'<br />
- To receive response from device, drivers need to listen this address (so-called allocation).<br />
<br />
12.AV/C commands<br />
- 'AV/C commands' is an application of 'Function Cotrol Protocol'.<br />
- The maximum size of command is 512 bytes.<br />
- There are much variations, vendor-specific extensions.<br />
- Basically, see 'AV/C Digital Interface Command Set General Specification Version 4.2 (Sept 2004, 1394TA)'.<br />
- For Audio Subunit, see 'AV/C Audio Subunit Specification 1.0 (Oct 2000, 1394TA)'.<br />
- For Music Subunit, see 'AV/C Music Subunit Specification 1.0 (I don't have)'.<br />
- For Stream Format, see 'AV/C Stream Format Information Specification 1.0 (I don't have)'<br />
- For Descriptor Mechanism, see 'Enhancements to the AV/C General Specification 3.0 Version 1.1 (Oct 2000, 1394TA)'.<br />
<br />
13.Sampling Clock Synchronization<br />
- This is device-dependent issue.<br />
- Usually Firewire Sound Devices use internal clock.<br />
- But some devices can switch its source of sampling clock. <br />
- There is Coaxial, Optical and XLR interface for this purpose.<br />
- And there is 'Synchronization Stream'. In this stream, the value of 'SYT' field can be used for sampling clock.<br />
- When source of clock is given by external, available sampling rate is limited at current one.<br />
<br />
14.Quirks<br />
- Fireworks:<br />
- 1.Fireworks transmits packets with both TAG0 and TAG1. In IEC 61883-1, each common isochronous packet (CIP) has 'tag' field in its packet header. The value is generally 0x01 ('CIP header is included' = TAG1). But Fireworks in 'IEC 61883 compliant mode' transmits 'no data' packet with 0x00 ('No CIP header is included' = TAG0) but actually the packet includes CIP structure. To handle 'presentation timestamp' for duplex streams synchronization, this packets must be handled.<br />
<br />
- 2.Fireworks transmits 'no data' packet out of specification. Fireworks transmits 'no data' packet with 'NO-DATA' FDF and no dummy data. It includes CIP headers only. In IEC 61883-6, 'no data' packet is generated by two ways. One is empty CIP packet defined in IEC 61883-1. Another is 'special non-empty packet' defined in IEC 61883-6. Fireworks uses strange combination of them.<br />
<br />
- 3.Fireworks can handle MIDI messages in the first 8 data blocks of out-packet, Fireworks ignores MIDI messages in other data blocks.<br />
<br />
- 4.AudioFirePre8 transmits packets with wrong data block size. One of Fireworks device, AudioFirePre8, always reports 8 data block size in transmitted packets and increments the data block counter by 8. But this is not actual value.<br />
<br />
- 5.Fireworks transmits packets with a bit disorder. See:<br />
<pre><br />
Index Payload CIP header 1CIP header 2<br />
023 210 3F1100F8 900478E9<br />
024 002 3F1100F8 90FFFFFF<br />
025 210 3F110000 900490E9<br />
026 210 3F110008 9004A4E9<br />
027 210 3F110010 9004B8E9<br />
028 002 3F110010 90FFFFFF<br />
029 210 3F110020 9004E4E8 <-<br />
030 210 3F110018 9004D0E8 <-<br />
031 210 3F110028 9004F8E8<br />
032 002 3F110028 90FFFFFF<br />
033 210 3F110030 900410E8<br />
034 210 3F110038 900424E8<br />
035 210 3F110040 900438E8<br />
036 002 3F110040 90FFFFFF<br />
037 210 3F110050 900464E8 <-<br />
038 210 3F110048 900450E8 <-<br />
039 210 3F110058 900478E8<br />
040 002 3F110058 90FFFFFF<br />
041 210 3F110068 9004A4E8 <-<br />
042 210 3F110060 900490E8 <-<br />
043 210 3F110070 9004B8E8<br />
044 002 3F110070 90FFFFFF<br />
045 210 3F110080 9004E4E7 <-<br />
046 210 3F110078 9004D0E8 <-<br />
</pre><br />
<br />
- BeBoB<br />
- BeBoB has its own AV/C extension command<br />
<br />
- OXFW970/971<br />
- OXFW970/971 transmit packets with invalid value of 'SYT' field. See:<br />
<pre><br />
When driver gives no out-stream:<br />
Index Payload CIP_Header_0 CIP_Header_1<br />
38 14 00020092 900103D1<br />
39 12 00020098 900102FF<br />
40 12 0002009D 9001027F<br />
41 14 000200A2 90010396<br />
42 14 000200A8 900102E8<br />
43 12 000200AE 90010219<br />
44 14 000200B3 90010331<br />
45 12 000200B9 9001025F<br />
46 14 000200BE 90010376<br />
47 12 000200C4 900102A1<br />
00 12 000200C9 9001023E<br />
01 14 000200CE 90010358<br />
02 12 000200D4 90010289<br />
03 16 000200D9 900103A3<br />
04 12 000200E0 900102DD<br />
05 14 000200E5 900103F1<br />
06 12 000200EB 90010335<br />
07 12 000200F0 90010263<br />
08 14 000200F5 9001037C<br />
09 12 000200FB 900102AE<br />
</pre><br />
<br />
<pre><br />
When driver gives out-stream:<br />
Index Payload CIP_Header_0 CIP_Header_1<br />
38 12 000200BD 900104A8<br />
39 14 000200C2 900104A8<br />
40 12 000200C8 900104AC<br />
41 14 000200CD 900104A9<br />
42 12 000200D3 900104B1<br />
43 14 000200D8 900104A8<br />
44 12 000200DE 900104AA<br />
45 14 000200E3 900104A9<br />
46 14 000200E9 900104AE<br />
47 12 000200EF 900104A8<br />
00 14 000200F4 900104AD<br />
01 12 000200FA 900104A7<br />
02 14 000200FF 900104A9<br />
03 12 00020005 900104A9<br />
04 14 0002000A 900104B1<br />
05 12 00020010 900104AA<br />
06 14 00020015 900104AD<br />
07 12 0002001B 900104A7<br />
08 14 00020020 900104AC<br />
09 12 00020026 900104A7<br />
</pre><br />
<br />
End</div>Takaswie