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UVC and UVA

WJCarpenter • 5 days ago • 0 comments

I don't know whether to file this under "learn something new every day" or "teach an old dog new tricks", but I recently looked into a standard called USB video device class (UVC) published by the USB Implementers Forum. (There is a companion standard, UAC, for audio, but I haven't looked at that.) The dongles based on the MS2109 and MS2130 chips advertise UVC and UAC compatibility, but I didn't really know what that meant beyond "don't need to install custom drivers". The dongles also expose a USB HID device, and I had assumed that any configuration control of them would be via the USB HID. Not so.

UVC is one of those standards where any particular devices is likely to only implement some subset, and that is true of these dongles. UVC provides protocol elements for querying or changing lots of different configuration items. There are multiple open source utilities that can be used to interact with UVC devices. For example, yavta and v4l-utils. Here are some examples for my MS2130 dongle:

This reports the available video modes, resolutions, and frame rates (figures for frame rates are quotes as frame intervals, so 1/60 is 60fps):

$ sudo yavta --enum-formats /dev/video2
Device /dev/video2 opened.
Device `USB3 Video: USB3 Video' on `usb-0000:00:15.0-1' (driver 'uvcvideo') supports video, capture, without mplanes.
- Available formats:
    Format 0: YUYV (56595559)
    Type: Video capture (1)
    Name: YUYV 4:2:2
    Frame size: 1920x1080 (1/60, 1/50, 1/30, 1/20, 1/10)
    Frame size: 1600x1200 (1/60, 1/50, 1/30, 1/20, 1/10)
    Frame size: 1360x768 (1/60, 1/50, 1/30, 1/20, 1/10)
    Frame size: 1280x1024 (1/60, 1/50, 1/30, 1/20, 1/10)
    Frame size: 1280x960 (1/60, 1/50, 1/30, 1/20, 1/10)
    Frame size: 1280x720 (1/60, 1/50, 1/30, 1/20, 1/10)
    Frame size: 1024x768 (1/60, 1/50, 1/30, 1/20, 1/10)
    Frame size: 800x600 (1/60, 1/50, 1/30, 1/20, 1/10)
    Frame size: 720x576 (1/60, 1/50, 1/30, 1/20, 1/10)
    Frame size: 720x480 (1/60, 1/50, 1/30, 1/20, 1/10)
    Frame size: 640x480 (1/60, 1/50, 1/30, 1/20, 1/10)

    Format 1: MJPEG (47504a4d)
    Type: Video capture (1)
    Name: Motion-JPEG
    Frame size: 1920x1080 (1/60, 1/50, 1/30, 1/20, 1/10)
    Frame size: 1600x1200 (1/60, 1/50, 1/30, 1/20, 1/10)
    Frame size: 1360x768 (1/60, 1/50, 1/30, 1/20, 1/10)
    Frame size: 1280x1024 (1/60, 1/50, 1/30, 1/20, 1/10)
    Frame size: 1280x960 (1/60, 1/50, 1/30, 1/20, 1/10)
    Frame size: 1280x720 (1/60, 1/50, 1/30, 1/20, 1/10)
    Frame size: 1024x768 (1/60, 1/50, 1/30, 1/20, 1/10)
    Frame size: 800x600 (1/60, 1/50, 1/30, 1/20, 1/10)
    Frame size: 720x576 (1/60, 1/50, 1/30, 1/20, 1/10)
    Frame size: 720x480 (1/60, 1/50, 1/30, 1/20, 1/10)
    Frame size: 640x480 (1/60, 1/50, 1/30, 1/20, 1/10)

Video format: YUYV (56595559) 1920x1080 (stride 3840) field none buffer size 4147200$ sudo v4l2-ctl -d2 --set-fmt-video "pixelformat=MJPG

This switches the video mode from YUYV to MJPG

$ sudo v4l2-ctl -d2 --get-fmt-video
Format Video Capture:
    Width/Height      : 1920/1080
    Pixel Format      : 'YUYV' (YUYV 4:2:2)
    Field             : None
    Bytes per Line    : 3840
    Size Image        : 4147200
    Colorspace        : sRGB
    Transfer Function : Rec. 709
    YCbCr/HSV Encoding: ITU-R 601
    Quantization      : Default (maps to Limited Range)
    Flags             : 

$ sudo v4l2-ctl -d2 --set-fmt-video "pixelformat=MJPG"

$ sudo v4l2-ctl -d2 --get-fmt-video
Format Video Capture:
    Width/Height      : 1920/1080
    Pixel Format      : 'MJPG' (Motion-JPEG)
    Field             : None
    Bytes per Line    : 0
    Size Image        : 4147200
    Colorspace        : sRGB
    Transfer Function : Rec. 709
    YCbCr/HSV Encoding: ITU-R 601
    Quantization      : Default (maps to Full Range)
    Flags             :

These tools tend to think you already know what the various parameters mean, but they are quite handy once you get the hang of them. The settings seem to stick, at least for the specific dongle that I have. If I unplug it and replug it, it remembers what I last set. The bad news is that the video playing software that I have handy (vlc and ffplay) seem to want to tweak some of the UVC settings, probably to better suit how they...

syslog for MS2130 dongle

WJCarpenter • 05/24/2024 at 00:20 • 0 comments

When plugging the MS2130-based HDMI capture dongle, /var/log/syslog says this:

2024-05-23T17:05:32.366859-07:00 yogi kernel: [14895.900908] usb 2-1: new SuperSpeed USB device number 5 using xhci_hcd
2024-05-23T17:05:32.398878-07:00 yogi kernel: [14895.933905] usb 2-1: LPM exit latency is zeroed, disabling LPM.
2024-05-23T17:05:32.422841-07:00 yogi kernel: [14895.956505] usb 2-1: New USB device found, idVendor=345f, idProduct=2130, bcdDevice=31.00
2024-05-23T17:05:32.422889-07:00 yogi kernel: [14895.956531] usb 2-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
2024-05-23T17:05:32.422895-07:00 yogi kernel: [14895.956540] usb 2-1: Product: USB3 Video
2024-05-23T17:05:32.422899-07:00 yogi kernel: [14895.956546] usb 2-1: Manufacturer: UltraSemi
2024-05-23T17:05:32.422902-07:00 yogi kernel: [14895.956552] usb 2-1: SerialNumber: 20210623
2024-05-23T17:05:32.438897-07:00 yogi kernel: [14895.973543] usb 2-1: Found UVC 1.00 device USB3 Video (345f:2130)
2024-05-23T17:05:32.498521-07:00 yogi kernel: [14896.032696] hid-generic 0003:345F:2130.000A: hiddev0,hidraw1: USB HID v1.10 Device [UltraSemi USB3 Video] on usb-0000:00:15.0-1/input4
2024-05-23T17:05:32.503063-07:00 yogi mtp-probe: checking bus 2, device 5: "/sys/devices/pci0000:00/0000:00:15.0/usb2/2-1"
2024-05-23T17:05:32.503640-07:00 yogi mtp-probe: bus: 2, device: 5 was not an MTP device
2024-05-23T17:05:32.592287-07:00 yogi (udev-worker)[16747]: controlC1: Process '/usr/sbin/alsactl -E HOME=/run/alsa -E XDG_RUNTIME_DIR=/run/alsa/runtime restore 1' failed with exit code 99.
2024-05-23T17:05:32.603188-07:00 yogi systemd[4030]: Reached target sound.target - Sound Card.
2024-05-23T17:05:32.606696-07:00 yogi mtp-probe: checking bus 2, device 5: "/sys/devices/pci0000:00/0000:00:15.0/usb2/2-1"
2024-05-23T17:05:32.606803-07:00 yogi mtp-probe: bus: 2, device: 5 was not an MTP device
2024-05-23T17:05:32.715245-07:00 yogi wireplumber[4049]:  Failed to call Lookup: GDBus.Error:org.freedesktop.portal.Error.NotFound: No entry for camera

A relevant detail is that it has both the video and audio device stuff, but it also has a HID interface. There is some reverse engineered work for doing things via that HID interface here: https://github.com/BertoldVdb/ms-tools

In contrast, when plugging the device into a USB 2.0 port, it's logged as:

2024-05-24T10:47:05.913518-07:00 yogi kernel: [42791.625745] usb 1-4.2: new high-speed USB device number 13 using xhci_hcd
2024-05-24T10:47:06.093496-07:00 yogi kernel: [42791.807407] usb 1-4.2: New USB device found, idVendor=345f, idProduct=2130, bcdDevice=21.00
2024-05-24T10:47:06.093516-07:00 yogi kernel: [42791.807417] usb 1-4.2: New USB device strings: Mfr=1, Product=5, SerialNumber=7
2024-05-24T10:47:06.093520-07:00 yogi kernel: [42791.807419] usb 1-4.2: Product: USB2 Video
2024-05-24T10:47:06.093521-07:00 yogi kernel: [42791.807421] usb 1-4.2: Manufacturer: UltraSemi
2024-05-24T10:47:06.093521-07:00 yogi kernel: [42791.807423] usb 1-4.2: SerialNumber: 20210621
2024-05-24T10:47:06.113028-07:00 yogi kernel: [42791.826992] usb 1-4.2: Found UVC 1.00 device USB2 Video (345f:2130)
2024-05-24T10:47:06.183876-07:00 yogi kernel: [42791.897291] hid-generic 0003:345F:2130.0013: hiddev0,hidraw6: USB HID v1.10 Device [UltraSemi USB2 Video] on usb-0000:00:15.0-4.2/input4
2024-05-24T10:47:06.187848-07:00 yogi mtp-probe: checking bus 1, device 13: "/sys/devices/pci0000:00/0000:00:15.0/usb1/1-4/1-4.2"
2024-05-24T10:47:06.188320-07:00 yogi mtp-probe: bus: 1, device: 13 was not an MTP device
2024-05-24T10:47:06.286059-07:00 yogi (udev-worker)[77117]: controlC1: Process '/usr/sbin/alsactl -E HOME=/run/alsa -E XDG_RUNTIME_DIR=/run/alsa/runtime restore 1' failed with exit code 99.
2024-05-24T10:47:06.315144-07:00 yogi mtp-probe: checking bus 1, device 13: "/sys/devices/pci0000:00/0000:00:15.0/usb1/1-4/1-4.2"
2024-05-24T10:47:06.315285-07:00 yogi mtp-probe: bus: 1, device: 13 was not an MTP device

To round things out, here's how the MS2109 dongle is logged (it only...

The five hurts
WJCarpenter • 05/22/2024 at 01:39 • 0 comments
I figured out what's up with the 5fps over the cheap dongle I have. In fact, I ordered a second, newer looking dongle, and it also gave me only 5fps.

Essentially all of these low-cost HDMI-to-USB dongles are based on the Macro Silicon MS2109 chip. It took some sleuthing, but I eventually found a datasheet for that chip. The chip has two output modes: YUV422 and MJPEG. MJPEG is what we really want, and the chip can output up to 1920x1080@30fps. In YUV422 mode, it's limited to 1920x1080@5fps. The dongles (at least the ones that I have) are configured for YUV422 mode, and that can't be changed without modifying the firmware in EEPROM. I don't know why the manufacturers selected that very limited output format.

Meanwhile, it looks like the go-to chip for the recent generation of those dongles is the Macro Silicon MS2130 (datasheet). In addition to the faster USB 3.0 interface, it supports output of 1920x1080@60fps for both YUV422 and MJPEG outputs. (The datasheet says the chip can be programmed to output 4K@15fps, but I haven't seen that mentioned in any advertisements for these things.

The older MS2109 dongles can be had for around US$10, and the newer MS2130 dongles go for around US$20. For this sort of project, that price difference doesn't matter too much. I got a dongle with an MS2130 chip:
```
Bus 002 Device 094: ID 345f:2130 UltraSemi USB3 Video
```
It does, indeed, emit video at FHD@60fps.

I could wish that it emitted MJPEG, but at least I am seeing the full resolution and frame rate.
Expensive-ish HDMI encoder
WJCarpenter • 05/18/2024 at 22:54 • 0 comments

When I started thinking about this cheap encoder project, I assumed it was more likely than not that it wouldn't be good enough for household TV watching. To hedge my bets, I ordered a standalone HDMI encoder box. It's this one:

I selected this one according to the Cheap and Lazy algorithm. I saw it mentioned by some other people, and it was inexpensive relative to others mentioned. It was also readily available with just a short delay. The day I bought it, there was also an instant coupon for US$20 off the price.

I ran the same sort of POC test with this device that I ran with the cheap encoder dongle earlier. Results were pretty good. Here is what vlc says about the stream:

vlc was able to consume and display a very clear image with both H.264 and H.265 codecs. Despite best efforts, I was only able to get a frame rate of 30fps. I'm not sure if that's a limitation of the device, a limitation of the Fire TV stick, or some other settings thing. The video and audio were completely smooth in vlc.

As a side note, there was some small inconvenience as a side effect of buying the least expensive device. The setup instructions are for Windows (whatever that is), and the device comes configured with a static IP address of 192.168.1.120. I already have a device with that address, so I had to temporarily turn it off while I configured this new device. Luckily, there is a simple web UI that lets you change the network configuration and various other things. There was an unexpected bonus (because I didn't pay attention to it while shopping). The device can record to an SD card for subsequent download. I don't know if I'll ever use that, but it's nice to have.

Regardless of what happens with this overall project, I should be able to scratch my single-channel itch with this device after applying some software magic.
Proof of concept
WJCarpenter • 05/17/2024 at 22:28 • 0 comments
Do those dongles actually work, and are they better than "marginally above crap"? Let's see what we can see.

When I plug the dongle into my Linux machine, it shows up as this USB device:
```
Bus 001 Device 038: ID 534d:2109 MacroSilicon
```
Searching around for those ID strings leads to the MacroSilicon MS2109 chip that powers the dongle that I have. I haven't pursued the innards of this chip, but it was easy to figure out that it's supported by the Linux v4l subsystem and presents as a pair of video devices.
```
crw-rw----+ 1 root video 81, 2 May 17 11:36 /dev/video2
crw-rw----+ 1 root video 81, 3 May 17 11:36 /dev/video3
```
At this point, I just needed any old HDMI video signal. I plugged in an Amazon Fire TV stick that was in my "send to the thrift store" box. I used vlc to open /dev/video2 as a capture device.

Hey, that worked! You can't see it, but the audio also played correctly. On my 4k monitor, that window with the FHD video doesn't look completely sharp, but it's good enough for the POC. Here's what vlc says about it:

The resolution is FHD (1920x1080), but it's only 5fps. The playing video has the choppy look that you'd expect from that frame rate. My quad-core low-powered Linux box reports about 30-50% on each core.
It didn't really prove anything that I didn't already know was OK, but I also streamed that video. My first attempt was to use mjpg-streamer, which I had used in an earlier project., but some python thing was giving me a hard time today. Instead, I used µStreamer, which is part of the PiKVM project. It doesn't include audio for this kind of setup, but I was able to view the playing video in a web browser.

Next steps: I've ordered a newer dongle that has a USB 3.0 interface, and I have some beefier Linux boxes to try. I am cautiously optimistic.
The HDMI dongles
WJCarpenter • 05/17/2024 at 22:01 • 0 comments

There are dongles that take HDMI input and plug into a USB port for output, and they are extremely cheap. They are readily available online for US$10-20. I've had one that looks like this for several years:
Until today, I'd never plugged it in. It was probably pretty cheap and I bought it for hazy future use after seeing it mentioned in some article somewhere. The future is now! The documentation that came with it claims it can accept an input of 4K@30fps and output FHD@30fps. I don't know if that claim is actually true. Even if it is, 30fps is less than desirable for watching TV. Newer iterations of similar dongles claim to output up to FHD@60fps. My TV is only FHD, not 4K, so FHD@60fps would be fine for now if it turns out to be true.
The DVR
WJCarpenter • 05/17/2024 at 21:52 • 0 comments

DVR, I hear you ask. These days, it's relatively easy to create your own DIY DVR with inexpensive hardware. For example, a Raspberry Pi with a couple of USB hard drives is enough computer power. Digital tuners are available for receiving OTA programming. The most well-known is HDHomeRun, but there are others. Many paid programming services also make their live TV content available for streaming via a technology called TV Everywhere. For the software, I've experimented with Channels DVR, emby, and a few others. None are perfect, but several are good enough.

One of the side-effects of these various DIY DVR efforts is that the people involved, both the developers and the users, have lots of interesting ideas for how to deal with programming. It is some of those ideas that I am exploring in this project. In particular, it's aspects of these very long discussion threads in the Channels DVR community forums that set me to thinking.
BETA: Chrome Capture for Channels
HDMI for Channels
ADBTuner: A “channel tuning” application for networked Google TV / Android TV devices