Tweet
HDV Motion Artifacting
Here are some examples of articles written about the topic:
1. http://tinyurl.com/eqnzu
"Motion, especially fast-moving and detailed motion as in sports footage, presents quite a challenge for the real-time MPEG encoders in standard HDV cameras."
"It’s a challenge HDV can often meet, but not always."
"This is the downside of HDV’s impressive MPEG compression efficiency."
2. http://tinyurl.com/h6qwu
"Shooting with the Sony HDR-FX1, we noticed that the image quality, although generally very good, becomes a bit noisy (or blurred) when we panned with the camera."
"Actually, this is quite typical for MPEG-2 compression, even in HD broadcasts, as we noticed in the Summer Olympics broadcasts."
"With the HDR-FX1, the blur/noise is more visible because it features a less expensive codec."
"Using an HD-SDI converter, we then hooked up the camera with a portable HDCAM deck (SONY HDW-250)."
"This let us bypass the MPEG-2 codec (with a transfer rate of 25 Mbps) and, instead, record uncompressed HD (with a rate of 140 Mbps)."
"This resulted in a higher image quality with relatively clean pans."
"Based on our experience, we also recommend minimizing horizontal movement (panning) as much as possible in order to maintain a clean image."
"If you need to pan (and want to maintain the image quality), always pan as slowly as possible!"
3. http://tinyurl.com/zn7c3
John Beale -- author of the famous Web site about the old Sony DCR-TRV900 -- now uses HDV camcorders, but when he down-converts to standard definition, he has to apply blur filters to the down-converted HDV to overcome unique issues (click the preceding link to read about those).
4. http://tinyurl.com/bedru
Wikipedia:
"Compared to more expensive HDCAM and DVCPRO HD equipment, HDV suffers from significantly more spatial and temporal (motion) artifacts."
"As a consequence of interframe (temporal) compression, HDV editing is more complex, and introduces greater distortion at the splice point (due to the interdependence of adjacent video frames.)"
"Compared to conventional SD DV, HDV offers a much higher spatial resolution, so most observers are willing to accept the artifacts in exchange for a higher-definition picture."
5. http://tinyurl.com/ehcum (by DV MAGAZINE's Adam Wilt)
"HDV looks very good for scenes of low to moderate complexity and unhurried motion."
"But a lot of high-frequency detail and/or abrupt, complex motions cause noticeable degradation in the form of posterization, blocking, and pseudo-random noise."
"Unlike DV, where the most noticeable artifact is localized 'mosquito noise' around areas of high detail, HDV's artifacts can permeate the entire frame, and are scene dependent in their characteristics."
"Furthermore, each frame's quality varies with the complexity of the other 14 frames in its Group of Pictures (for 1080i; 720p uses a 6-frame GOP), so there's a time dependency to HDV's artifacts that's absent in DV."
"After a couple of months of working with the HDR-FX1, I still get surprised at how certain scenes react to HDV's compression."
"For the most part, an HDV camera original tape played back at 1 x speed looks quite good, with artifacts adding a feeling of overall noise rather than appearing as noticeable, localized defects."
"However, the 'noise' buildup on busy scenes is noticeable."
(The preceding comments are from Adam Wilt and I agree with him. - JJ)
6. http://tinyurl.com/guz3s
Excerpt from Larry Jordan's Final Cut Pro Newsletter:
Jerry Jones
1. http://tinyurl.com/eqnzu
"Motion, especially fast-moving and detailed motion as in sports footage, presents quite a challenge for the real-time MPEG encoders in standard HDV cameras."
"It’s a challenge HDV can often meet, but not always."
"This is the downside of HDV’s impressive MPEG compression efficiency."
2. http://tinyurl.com/h6qwu
"Shooting with the Sony HDR-FX1, we noticed that the image quality, although generally very good, becomes a bit noisy (or blurred) when we panned with the camera."
"Actually, this is quite typical for MPEG-2 compression, even in HD broadcasts, as we noticed in the Summer Olympics broadcasts."
"With the HDR-FX1, the blur/noise is more visible because it features a less expensive codec."
"Using an HD-SDI converter, we then hooked up the camera with a portable HDCAM deck (SONY HDW-250)."
"This let us bypass the MPEG-2 codec (with a transfer rate of 25 Mbps) and, instead, record uncompressed HD (with a rate of 140 Mbps)."
"This resulted in a higher image quality with relatively clean pans."
"Based on our experience, we also recommend minimizing horizontal movement (panning) as much as possible in order to maintain a clean image."
"If you need to pan (and want to maintain the image quality), always pan as slowly as possible!"
3. http://tinyurl.com/zn7c3
John Beale -- author of the famous Web site about the old Sony DCR-TRV900 -- now uses HDV camcorders, but when he down-converts to standard definition, he has to apply blur filters to the down-converted HDV to overcome unique issues (click the preceding link to read about those).
4. http://tinyurl.com/bedru
Wikipedia:
"Compared to more expensive HDCAM and DVCPRO HD equipment, HDV suffers from significantly more spatial and temporal (motion) artifacts."
"As a consequence of interframe (temporal) compression, HDV editing is more complex, and introduces greater distortion at the splice point (due to the interdependence of adjacent video frames.)"
"Compared to conventional SD DV, HDV offers a much higher spatial resolution, so most observers are willing to accept the artifacts in exchange for a higher-definition picture."
5. http://tinyurl.com/ehcum (by DV MAGAZINE's Adam Wilt)
"HDV looks very good for scenes of low to moderate complexity and unhurried motion."
"But a lot of high-frequency detail and/or abrupt, complex motions cause noticeable degradation in the form of posterization, blocking, and pseudo-random noise."
"Unlike DV, where the most noticeable artifact is localized 'mosquito noise' around areas of high detail, HDV's artifacts can permeate the entire frame, and are scene dependent in their characteristics."
"Furthermore, each frame's quality varies with the complexity of the other 14 frames in its Group of Pictures (for 1080i; 720p uses a 6-frame GOP), so there's a time dependency to HDV's artifacts that's absent in DV."
"After a couple of months of working with the HDR-FX1, I still get surprised at how certain scenes react to HDV's compression."
"For the most part, an HDV camera original tape played back at 1 x speed looks quite good, with artifacts adding a feeling of overall noise rather than appearing as noticeable, localized defects."
"However, the 'noise' buildup on busy scenes is noticeable."
(The preceding comments are from Adam Wilt and I agree with him. - JJ)
6. http://tinyurl.com/guz3s
Excerpt from Larry Jordan's Final Cut Pro Newsletter:
On the negative side, the weaknesses of HDV are:
* The HDV image is 1440 x 1080, which does not precisely match either the 720p or 1080i format.
* HDV is enormously compressed, creating the possibility of significant motion artifacts when the camera is moved, or zoomed, quickly. HDV uses MPEG-2 compression, the same as a DVD.
* This compression groups several pictures into a "group of pictures," called a GOP, rather than each picture being it's own entity. 1080i HD groups 15 images into one GOP. 720p groups 6 images into one GOP.
* This GOP method of compression means that HDV is not accurate for timecode or frames when capturing or outputting. (Editing HDV inside FCP is frame-accurate, however.)
* HDV uses extreme color sampling, resulting in very, very poor color keying, color correction, or compositing results. (HDV uses 4:2:0 color sampling, the same as a DVD. Here's an article that explains it in more detail.)
* HDV renders take about six times longer than DV. This is actually a result of rendering the larger HD image, versus an SD image; still, this will take longer than you expect.
* HDV needs to be conformed, or rebuilt, into a consistent GOP structure before it can be output to tape or exported to a file. This conforming can take an exceedingly long time. (For instance, conforming a 30 second sequence consisting of five shots, took over 10 minutes on my PowerBook. Conforming a complex hour-long sequence could take several hours on a G-5.)
* HDV can only use Print to Tape, not Edit to Tape, due to the timecode inaccuracies of HDV.
* The HDV image is 1440 x 1080, which does not precisely match either the 720p or 1080i format.
* HDV is enormously compressed, creating the possibility of significant motion artifacts when the camera is moved, or zoomed, quickly. HDV uses MPEG-2 compression, the same as a DVD.
* This compression groups several pictures into a "group of pictures," called a GOP, rather than each picture being it's own entity. 1080i HD groups 15 images into one GOP. 720p groups 6 images into one GOP.
* This GOP method of compression means that HDV is not accurate for timecode or frames when capturing or outputting. (Editing HDV inside FCP is frame-accurate, however.)
* HDV uses extreme color sampling, resulting in very, very poor color keying, color correction, or compositing results. (HDV uses 4:2:0 color sampling, the same as a DVD. Here's an article that explains it in more detail.)
* HDV renders take about six times longer than DV. This is actually a result of rendering the larger HD image, versus an SD image; still, this will take longer than you expect.
* HDV needs to be conformed, or rebuilt, into a consistent GOP structure before it can be output to tape or exported to a file. This conforming can take an exceedingly long time. (For instance, conforming a 30 second sequence consisting of five shots, took over 10 minutes on my PowerBook. Conforming a complex hour-long sequence could take several hours on a G-5.)
* HDV can only use Print to Tape, not Edit to Tape, due to the timecode inaccuracies of HDV.
Comment