Popular Post yamamoto2002 Posted November 26, 2018 Popular Post Share Posted November 26, 2018 If you have a digital input device, and your DAC have a digital output, you can test if the DAC accurately output data bits or occasionally output corrupted data, by yourself with WasapiBitmatchChecker. Connect DAC digital out to digital recorder input and perform loopback test... Following screenshot shows 12 hours of PCM data is sent using my $60 USB audio device and every output bits are correctly received by a PCM digital recording device. This test takes 12 hours to finish USB specification says, in the worst case 1 bit in 1000 000 000 000 bit may be corrupted. crenca, esldude, phosphorein and 6 others 9 Sunday programmer since 1985 Developer of PlayPcmWin Link to comment
yamamoto2002 Posted November 27, 2018 Share Posted November 27, 2018 13 hours ago, beerandmusic said: What about rankins testing in initial post... I read the article As Rankin-san said, it seems USB reliability becomes lower when many USB devices connected to one USB host controller. So maybe the error he experienced is caused by interference with other USB devices? (It should not be happened but in the real world, it happens) You may have a interest to the following experiment, Challenge to connect theoretical max number of USB devices to one Windows 7 PC. This 3 page document is full of nightmare experience with unreliable computer. He has a great patience. From 80 USB devices, computer becomes really unstable. http://ascii.jp/elem/000/000/720/720038/ This may be caused by CRC error (I don't have a equipment to confirm this so this is a guess) I have similar experience to the document with my PC. When a USB hub with several USB devices is connected to the PC, often the hub and all the subsequent USB devices is not recognized and reconnecting cures the problem. Sunday programmer since 1985 Developer of PlayPcmWin Link to comment
Popular Post yamamoto2002 Posted December 1, 2018 Popular Post Share Posted December 1, 2018 Musiland USB devices also uses bulk transfer. USB shares one bus to all USB devices connected to one host controller. In order to transfer 96kHz 24bit 2ch PCM (4.6Mbps) on USB 1.x FullSpeed bus (12Mbps) (in this case the PCM stream size is about 40% of USB bus bandwidth capacity), It is necessary to use a mechanism to allocate some length of time slot sorely for the audio data transfer before audio transfer starts and return it after use, isochronous transfer mechanism do the job. If bulk transfer is used, the amount of the data transferred varies on the bus traffic, it depends on other devices' transfer activity, maybe USB memory data transfer occupy 80% of the USB bus capacity. in this case, your bulk transfer USB Audio DAC cannot send 40% of the capacity audio data properly and playback stops or other glitch happens. But now host controller becomes USB 3.0 (5,000 Mbps), it has plenty room for spare, so bulk transfer can be used for USB Audio data transfer scenario unless USB bus is intentionally saturated Teresa, beerandmusic and One and a half 1 1 1 Sunday programmer since 1985 Developer of PlayPcmWin Link to comment
yamamoto2002 Posted December 1, 2018 Share Posted December 1, 2018 53 minutes ago, beerandmusic said: +1 Thanks for sharing...you clearly know a lot more than most here. To clarify in layman's terms, USB 3.0 because of higher speed, along with bulk transfer, is ideal? Can processing quad DSD on USB 2.0 be an issue if not properly managed?...e.g. is there ever a bigger concern with processing quad DSD as opposed to 44.1 PCM? PS are you a dac engineer? Do you see any advantage in doing fiber (e.g. the new LUMIN X1 with fiber input)? USB speed increased and bulk transfer becomes a new option for audio transfer. I'm not sure if it is ideal or not but there is a drawback, bulk transfer audio dac needs its proprietary device driver to be installed while operating system supplies stock device driver for isochronous USB audio devices. Quad DSD(23Mbps to 45Mbps) on USB 2.0(480Mbps) should not be an issue. I've tested it and it runs fine. I'm just another layman and a fan of optical link from 1990s S/PDIF because optical gear looks cool and futuristic, and long waiting the fibre version of thunderbolt. Sound quality may not changed very much but it has galvanic isolation as its advantage. asdf1000 1 Sunday programmer since 1985 Developer of PlayPcmWin Link to comment
yamamoto2002 Posted December 2, 2018 Share Posted December 2, 2018 I use generic 6ft certified Hi-Speed USB cable and it is practically error-free at least on my audio setup. esldude 1 Sunday programmer since 1985 Developer of PlayPcmWin Link to comment
yamamoto2002 Posted December 3, 2018 Share Posted December 3, 2018 I have only one isochronous synchronous USB audio device (while technically this is not a DAC). Isochronous PCM data size = 48000Hz * 2ch * 2 bytes (16bit) / 1000 = 192 bytes / 1ms Sunday programmer since 1985 Developer of PlayPcmWin Link to comment
Popular Post yamamoto2002 Posted December 3, 2018 Popular Post Share Posted December 3, 2018 2 hours ago, sandyk said: My understanding is that the USB inputs of earlier Oppo players such as my Oppo 103 weren't Async. However, I could be incorrect about this, Async was mentioned in the blurb for the 105. BDP-103 's all three Type-A USB ports support only USB Mass storage class devices such as USB memory and USB hard disk. those devices are bulk transfer, not isochronous transfer. BDP-103's DAC will work with its own local clock when sound source is placed on USB memory. BDP-105 have additional Type B USB port called "USB DAC" , it connect to PC and BDP-105 behaves as an USB DAC. it supports isochronous asynchronous transfer and BDP-105's DAC clock will be fed from local clock. If you use S/PDIF, TOSLINK or HDMI input, sender becomes clock master and receiver's (BDP-10x) audio DAC will operate as some sort of adaptive mode. Kyhl and pkane2001 2 Sunday programmer since 1985 Developer of PlayPcmWin Link to comment
yamamoto2002 Posted May 3, 2019 Share Posted May 3, 2019 On 5/2/2019 at 7:16 AM, Ralf11 said: What USB mode would be the absolute best for Audio transmissions ? I read somewhere RME person tried interrupt transfer and found it does not deliver sufficient data rate for audio use. Sunday programmer since 1985 Developer of PlayPcmWin Link to comment
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