What difference if any would you expect to see between footage recorded on a prosumer HD camcorder to the on-board hard disk or SD card compared to what could be squeezed out of footage exporterd via mini HDMI to an external recorder? Is it likely that both recording modes would be subject to the same internal compression before reaching their destination or is it possible that the HDMI output could be less compressed and therefore provide at least a different if not better image quality?
Recording via HDMI vs SD card?
- Thread starter lowep
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Nate Haustein
Well-known member
In my experience with Canon Vixia-type cameras, it makes a difference, but not that much of a difference. Less compression but still only 8-bit and limited to the capabilities and front-end of the camcorder itself. All you need to do is plug your camcorder HDMI directly into an HD television set to immediately see what difference it will make.
Thanks Nate for the helpful reply. So compression maybe changes when output is via HDMI? If I understand right my little TM300 caps out at 17Mbps that is quite a bit higher than 8. Not sure how this relates to compression but maybe starting out with a higher bit rate means in the end the difference outputting via HDMI is less noticeable. Looks like as you say the only way to find out is to hook up direct to a HD television and try to do an eyeball comparison of the results with footage captured on the SD card.
The TM300 does 24p in "digital cinema" mode but if I understand right this only changes the frame rate but does not make much difference to the image quality, right?
The TM300 does 24p in "digital cinema" mode but if I understand right this only changes the frame rate but does not make much difference to the image quality, right?
Looking into this further found this post on another website about another camcorder but nonetheless quite relevant:
[FONT="]"Live HDMI out isn't going to necessarily get you what you're looking for. First of all, while the footage isn't compressed to tape, it's very possible that it's compressed in-camera before reaching the HDMI port. You'll have to look into that (and in all honesty, that information is really hard to find)..."[/FONT]
Do you agree?
[FONT="]"Live HDMI out isn't going to necessarily get you what you're looking for. First of all, while the footage isn't compressed to tape, it's very possible that it's compressed in-camera before reaching the HDMI port. You'll have to look into that (and in all honesty, that information is really hard to find)..."[/FONT]
Do you agree?
Nate Haustein
Well-known member
Really not sure what happens on HDMI outputs for all lower end camcorders, but in my experience all mine have been 4:2:2, albeit 8-bits. Like I said, plug it into your tv and see how it looks following this process:
1. Record a bit of your living room/office with AVCHD on the card and play it back on the tv.
2. Switch the camera back to record mode and see how your living room/office looks via live HDMI monitoring while plugged into the tv.
3. If live monitoring looks better than the recorded AVCHD, you have our answer. If you can't tell a difference, external recording may not be worth the trouble.
With my AF100 I could see the difference pretty easily. Playing back footage in AVCHD just didn't look as good as it did while being monitored live during recording on the TV set.
1. Record a bit of your living room/office with AVCHD on the card and play it back on the tv.
2. Switch the camera back to record mode and see how your living room/office looks via live HDMI monitoring while plugged into the tv.
3. If live monitoring looks better than the recorded AVCHD, you have our answer. If you can't tell a difference, external recording may not be worth the trouble.
With my AF100 I could see the difference pretty easily. Playing back footage in AVCHD just didn't look as good as it did while being monitored live during recording on the TV set.
Just found out TM300 gives 2 options in setup menu for HDMI output resolution: 1080i (same as to SD card & internal HD) or 576p that is only 36 full frames less than 1080i, right, so this supports your first suggestion Nate that outputting to HDMI probably "makes a difference, but not that much of a difference". Unless the output to HDMI route can be used to record the same 1080i or 576p with a different codec with less harsh compression than AVCHD?
Barry_Green
Moderator
I don't know of any cameras that compress the footage, and then uncompress it, and output that result over their HDMI ports. I'm not saying it's impossible, but I'm saying I've never heard of that. As far as I know most cameras, if not all cameras, are putting a clean/uncompressed signal out to their monitor ports. Now, that doesn't mean the signal is worthy of recording; it may just be a lousy output (as most DSLRs had in the early years). Or it may be muddled with pulldown field issues (like the GH2). But most conventional camcorders should have uncompressed clean HDMI outputs as far as I've found.
Does that mean the results will be better with an external recorder? Probably, but (as Nate said, and as we've extensively tested with other cameras) it doesn't make THAT big of a difference. Recording 220mbits of prores can result in retaining more image detail than recording 21 megabits of AVCHD, and certainly would result in better quality than 25 megabits of HDV, but it also really depends on what you're shooting. Most people would be hard pressed to tell the difference between the internal recording, or an HDMI recording, of a standard talking-head interview, for example.
Does that mean the results will be better with an external recorder? Probably, but (as Nate said, and as we've extensively tested with other cameras) it doesn't make THAT big of a difference. Recording 220mbits of prores can result in retaining more image detail than recording 21 megabits of AVCHD, and certainly would result in better quality than 25 megabits of HDV, but it also really depends on what you're shooting. Most people would be hard pressed to tell the difference between the internal recording, or an HDMI recording, of a standard talking-head interview, for example.
"depends on what you're shooting..."
this is exactly my concern...:thumbup:
rather than standard talking head interviews, would you guess outputting to a recorder with a different codec via hdmi rather than avchd to SD or internal HD would make any difference in any of the following scenarios:
1. smudging and artifacts from filming in low light with (too) much gain
2. high contrast resulting in burned out highlights and/or lost detail in shadows
3. flat colors in bright light
all these problems could probably be countered by upgrading from a prosumer camera to a more professional one but apart from these specific IQ issues and occasional problems tracking movement am otherwise quite happy with what I already have
this is exactly my concern...:thumbup:
rather than standard talking head interviews, would you guess outputting to a recorder with a different codec via hdmi rather than avchd to SD or internal HD would make any difference in any of the following scenarios:
1. smudging and artifacts from filming in low light with (too) much gain
2. high contrast resulting in burned out highlights and/or lost detail in shadows
3. flat colors in bright light
all these problems could probably be countered by upgrading from a prosumer camera to a more professional one but apart from these specific IQ issues and occasional problems tracking movement am otherwise quite happy with what I already have
demoboy
Well-known member
There's definitely a better difference in quality and it's all about how compression affects an image. Let's say we're working with a cam that's marketing its specs as 4:2:0 8-bit internal and it has an "uncompressed" external stream via HDMI out (which just means its not being "compressed") is good enough to work with. The main reason this is good is because bit rates are not varied or as we say "VBR." VBR and motion are interconnected with AVCHD. 28mbs is not good enough for consistent fresh capture like 50mbs. If 2 seconds of recorded footage runs down to 18mbs from 24mbs affects the image. Uncompressed 220mbs is nice. Or 4:2:2 8-bit 50mbs is better than AVCHD 2.0
RRRoger
Well-known member
Many/most of the new cameras offer uncompressed HDMI out.
On these, it you do lots of "Post Processing" there can be a huge difference.
There is also a huge amount of equipment, storage, and work involved.
So, the intended final use should decide whether it is worth it.
In my case, I have my GH4 set for internal AVCHD 28mbps recording at 1080 P60.
I critique the original files on my ultra high def computer screen before burning DVD and Blue Ray disc for TV viewing.
I doubt you could tell the difference on your TV between these and ones produced from RAW or 220mbps files.
I say this because I have worked with 220mbps files before.
On these, it you do lots of "Post Processing" there can be a huge difference.
There is also a huge amount of equipment, storage, and work involved.
So, the intended final use should decide whether it is worth it.
In my case, I have my GH4 set for internal AVCHD 28mbps recording at 1080 P60.
I critique the original files on my ultra high def computer screen before burning DVD and Blue Ray disc for TV viewing.
I doubt you could tell the difference on your TV between these and ones produced from RAW or 220mbps files.
I say this because I have worked with 220mbps files before.
Michael Carter
Veteran
Well, the GH4 does offer 10 bit out via HDMI, I don't know if any other DSLRs do.
In the image examples posted above, where several were issues of dynamic range... those may be more of a sensor issue in many cameras.
Like Barry said, test... and there are plenty of A/B tests out there. Some Nikon DSLRs get improved shadow noise, for instance, but overall nothing I've seen has been a big leap up in quality. The GH4 should be an exception, or at least it seems like it on paper.
I would like to test a Ninja or something with the D7100 - really some of the best off-the-card footage I've ever dealt with in keying. But so far only the higher-end 4K recorders can do 1080p @ 60, so there's that limitation if you do a lot of music videos, fashion/beauty, effects or industrial stuff.
In the image examples posted above, where several were issues of dynamic range... those may be more of a sensor issue in many cameras.
Like Barry said, test... and there are plenty of A/B tests out there. Some Nikon DSLRs get improved shadow noise, for instance, but overall nothing I've seen has been a big leap up in quality. The GH4 should be an exception, or at least it seems like it on paper.
I would like to test a Ninja or something with the D7100 - really some of the best off-the-card footage I've ever dealt with in keying. But so far only the higher-end 4K recorders can do 1080p @ 60, so there's that limitation if you do a lot of music videos, fashion/beauty, effects or industrial stuff.
RRRoger
Well-known member
If you live near Prunedale or Monterey Bay, you can borrow my Shuttle II and Ninja II and knock yourself out.
I would be interested in your results.