Cat,
This is a really welcome Post.
I have ‘played’ with several video capture devices over the years and often found them to be frustrating due to image quality issues, driver instability on particular operating systems or just plain junk that does not work !
My first ever capture solution was the ATI “All In Wonder Pro” combined PC video and capture ISA card. It did what it was supposed to do and, for its time, produced excellent captures. I then moved onto a Pinnacle PCI card and that worked well with no issues. It was only when I moved to the convenience of USB connectivity that the trouble started !
Some general comments on USB capture devices from my previous experiences.....
1. There are USB 1.1 and USB 2.0 versions commonly available. USB 2.0 should be considered a minimum speed and newer USB 3.0 are likely better for higher resolution, high frame rate captures. It just comes down to the maths of moving all those pixels into the host PC with the overhead of USB packet transfer to be considered. Poor transfer rates can lead to dropped frames and sometimes a capture card will reduce capture quality if the USB data rate is poor. Hence why USB 2.0 or better devices are a good idea. FireWire was an excellent data link for video capture but is now obsolete. USB3.0 is fast enough for demanding tasks.
2. It is important to discover the chipset that is used in a USB capture device. Whilst it may be new and shiny on the outside, it can contain an old and relatively poor performance chipset. Drivers can become an issue for some older chipsets, especially for Win10. The newer chipsets offer ‘system on a chip’ highly integrated video capture and have made the complex process of capturing video into a PC simple for hardware manufacturers. The chip takes video of many types in on one side and spits out USB packets on the other side
This thread may help us to identify which chipsets perform well, and which are to be avoided.
3. The small USB video capture dongles often have a sealed case and no ventilation. They can get quite hot whilst in use and this does not bode well for longevity. If you do a lot of video capture work, there may be justification in fitting a better case to the dongle that provides ventilation. Alternatively, some ventilation holes may be added to the original case. Some USB TV capture dongles had ventilation slots and that seems a sensible idea to me. Chips that are working hard and getting too hot can misbehave, throttle their speed or even hang.
4. There are some VERY cheap video capture dongles available on eBay etc. In my experience these use the cheapest available chipset and components so do not expect such a unit to provide the best capture performance. Hence my warning about old chipsets and USB 1.1 data links. It is not only the video capture image quality that can be poor, it can also be the frame rate, available capture resolution and the occurrence of many dropped frames as the chipset struggles in its task to convert the analogue TV signal accurately into the digital domain and packetise it for transfer to the host computer. This is not to say you must pay a lot of money to get a decent USB video capture dongle. There are many reasonably priced solutions that will perform well without breaking the bank. There have been excellent advances in video capture silicon in recent years, hence my warning to maybe avoid older chipsets unless they are known to perform well. In my experience, the maximum capture resolution and frame rate can be a hint at the performance of the chipset. 320 x 240 at 15fps = one to avoid ! A more capable chipset will offer at least 640 - 480 pixels with a choice of frame rates to suit the requirements of the user. My old Matrox MXO2 Mini from 2010 offers up to 1080p at a range of high frame rates including the 24fps used for film transfers at the correct speed. That unit was very expensive in its day but there must be similar available now and likely at a much reduced cost. I cannot recommend the Matrox MXO2 as it is long out of support and was effectively abandoned at Windows7.
5. Connectivity ...... a video capture card or dongle can offer a range of video inputs (and outputs in some cases). The simplest capture devices use a composite video signal. This is the lowest quality signal that you will find on AV equipment. That said, it is likely what you will have to work with on thermal cameras that provide an analogue video output ! For information, in terms of quality this is the list from worst to best.....
Composite Video - Y/C (S-Video) - RGB - Component - HDMI
SDI will be in the area of HDMI I suspect and is found on professional camera equipment.
6. Monochrome video - This week I used an EZCap USB 2.0 dongle to capture video from a monochrome output SWIR camera. The dongle is actually a decent model but it did not like the monochrome video input and claimed no signal was present when I tried to record. I fooled the units input checks using a colour bar chart video input from my CCTV test monitor before swapping the signal to the camera output. It was a faf to do and highlights that modern video capture chipsets MAY have an issue with missing parts of a signal that they expect to find, such as the colour burst. Video capture devices offer several Television Signal standards in their input configuration but on my dongle all were colour and there was no option for a monochrome PAL or NTSC signal. I know that other capture dongles do not have this issue so it may be uncommon or limited to a certain chipset. Some may not check the video input for anything except the sync pulses.
7. Video standards conversion...... thermal imaging cameras commonly present either a PAL or NTSC signal at their video output socket. The video capture device needs to be set for the video standard that is present. All of my capture devices support PAL, NTSC and SECAM without issues. The video standard can be changed in software when the recording is transferred to a DVD, Memory Stick etc. There is not normally a need to change the video standard with a hardware solution between the camera and the video capture device.
8. Video link standard conversion..... this is a new one for me so I can offer no in depth experience beyond a single test I carried out recently. I had a DVD recorder that provided only component, SCART RGB and SCART Composite video output. I needed an HDMI signal to feed into our new television. I bought a “Techole” SCART to HDMI converter from Amazon. It had good reviews. I installed the converter and was impressed that it was truly ‘plug and play’ with only the output resolution of 720P or 1080P to be selected with a push button. The unit up scaled the input video signal
Now the bad news. Whilst the converter worked well, I did some research and discovered that most inexpensive SCART to HDMI converters use a chip set that only accepts a composite video input, even if they have a SCART socket. This means that a video source that can provide RGB with better quality cannot deliver that improved image to the televisions HDMI input. More expensive converters will take component or RGB video inputs. Again, with a thermal camera the issue is moot as the output signal is often plain old composite video. In my case, I ‘dumped’ the elderly DVD recorder and bought a wonderful used Sony RDR-HXD870 HDD/DVD recorder that provides an upscaled 1080P HDMI output
Great recordings and great image quality on our new TV.
Using a camcorder as a capture device ...... For many years the UK camcorder market offered Camcorders that could only output line video and not record it. I believe this was due to the different Duty rates between line out only camcorders and video recorders as a camcorder with a video line input was classed as a VCR. You could buy the same model of camcorder overseas that had the video line input capability enabled ! I bought such camcorders but, in truth, rarely used the line input recording feature. My last camcorder was a Canon DV tape based unit and that had the line input recording enabled. The Camcorder could record analogue video from a video source and play that digitally recorded video back via its FireWire port to a host PC for editing etc. It could also do live real time conversion from analogue video source to DV output from its FireWire port. Is this a good option in place of a modern USB video capture device ? Well it is a solution but there are issues. The quality of video conversion may, or may not be as good as that of a dedicated USB video capture device. The resolution of video capture may also be relatively low. The video standard of the input to the camcorder may be fixed so not suitable for other video standard recordings. The Camcorder may have an inactivity shutdown feature that switches it off if not actually recording. FireWire is sadly now obsolete so less common on modern PC’s and laptops. It can still be added via a PCIe card or Expresscard however. The camcorder is a more bulky and complicated solution than buying a decent dedicated video capture device.
Well I think that is enough from me for now. I will correct the likely many typos in the above text later
Fraser
Home
Help
Search
Login
Register
