1) I would like to propose to be able to setup REW to measure from an external source in order to measure a sweep which is played back from another computer or device. When the measurement source is external, no internal signal generator will be used. Either the started measurement detects when it is complete, or it has a configurable "measurement time" window, e.g. 20s. Beta 24 supports playback from file, but you cannot turn off the output generator altogether.
2) I'd like to propose a "pre delay" setting in the signal generator in the sweep functions, sending silence prior to running the sweep in order to allowing the audio stream to stabilize before the actual measurement output is started.
My use case is as follows: I am trying to make some measurements on an AVR using HDMI input and measuring the analogue XLR output with a Focusrite USB sound card. To do this two computers are required: One for REW signal/sweep generation over HDMI to the AVR, and one to measure the sweep using the Focusrite input. It is currently impossible to do this from REW on one computer, as the HDMI clock source from the computer and the internal clock in the Focusrite are uncorrelated. (The Focusrite does, however support clock sync from SPDIF input, but the AVR doesn't have any SPDIF output that could act as a synchronization mechanism.) This is of course not a problem with REW, nor is it desirable to add a resampler into this chain.
The solution was to use REW from another computer to generate the measurement sweep using HDMI, while using REW on the first computer connected to the Focusrite to record the actual measurement. Measurements are done by pressing "Start" on the measurement dialog on both computers approximately simultaneously. Since the measurement process is a timed process by the "fake" output sweep generator, the measurement sometimes fails if the sweep is started too late on the generator computer. Curiously, I could have used the sweep function on the generator to generate the measurement sweep, but I found that difficult to use. The AVR needs a second to stabilize the audio stream, and the generator sweep simply starts too quickly. Thus I ended up using the full measurement dialog as a sweep generator on that computer too.
3) A third, perhaps more exotic option, would be to allow the measurement REW to control a signal generator REW on another computer. This would solve all timing and coordination issues that this setup have.
As always, John, thank you very much for your awesome tool.
Best regards,
Svein
2) I'd like to propose a "pre delay" setting in the signal generator in the sweep functions, sending silence prior to running the sweep in order to allowing the audio stream to stabilize before the actual measurement output is started.
My use case is as follows: I am trying to make some measurements on an AVR using HDMI input and measuring the analogue XLR output with a Focusrite USB sound card. To do this two computers are required: One for REW signal/sweep generation over HDMI to the AVR, and one to measure the sweep using the Focusrite input. It is currently impossible to do this from REW on one computer, as the HDMI clock source from the computer and the internal clock in the Focusrite are uncorrelated. (The Focusrite does, however support clock sync from SPDIF input, but the AVR doesn't have any SPDIF output that could act as a synchronization mechanism.) This is of course not a problem with REW, nor is it desirable to add a resampler into this chain.
The solution was to use REW from another computer to generate the measurement sweep using HDMI, while using REW on the first computer connected to the Focusrite to record the actual measurement. Measurements are done by pressing "Start" on the measurement dialog on both computers approximately simultaneously. Since the measurement process is a timed process by the "fake" output sweep generator, the measurement sometimes fails if the sweep is started too late on the generator computer. Curiously, I could have used the sweep function on the generator to generate the measurement sweep, but I found that difficult to use. The AVR needs a second to stabilize the audio stream, and the generator sweep simply starts too quickly. Thus I ended up using the full measurement dialog as a sweep generator on that computer too.
3) A third, perhaps more exotic option, would be to allow the measurement REW to control a signal generator REW on another computer. This would solve all timing and coordination issues that this setup have.
As always, John, thank you very much for your awesome tool.
Best regards,
Svein
