QT display all the quality of HD 1080p - or not?
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From: Mark Conrad on 19 Jun 2010 17:10 Notice when QT plays a HD video, it lists the video it is playing as MP4. Does this mean that QT can not play HD 1080p videos directly, instead has to convert HD 1080p to MP4 ? Confusing, at least to a video newbie like me. I like sharp video, the "usual" MP4 looks fuzzy to me, but these "converted" MP4s look noticably sharper. MP4 is MP4, right? How can some MP4s look sharper than others? (mutter, mutter) While I am complaining, why are there so many friggin different video formats, haven't these idjits ever heard of "KISS" ? Mark-
From: krishnananda on 19 Jun 2010 19:08 In article <190620101410018432%aeiou(a)mostly.invalid>, Mark Conrad <aeiou(a)mostly.invalid> wrote: > Notice when QT plays a HD video, it lists the video > it is playing as MP4. > > Does this mean that QT can not play HD 1080p videos > directly, instead has to convert HD 1080p to MP4 ? > > Confusing, at least to a video newbie like me. > > I like sharp video, the "usual" MP4 looks fuzzy to me, > but these "converted" MP4s look noticably sharper. > > MP4 is MP4, right? How can some MP4s look sharper > than others? (mutter, mutter) > > > While I am complaining, why are there so many friggin different > video formats, haven't these idjits ever heard of "KISS" ? > > Mark- MP4 (MPEG-4 Part 14, formally ISO/IEC 14496-14:2003) is a container format for audio and video encoded content. H.264/MPEG-4 AVC, for example, is the standard approved for BluRay HD disks. H.264 is the compression standard and MP4-AVC is the container. QuickTime is playing whatever is inside the container, not the container itself. Think of it as a TCP/IP packet -- the head and tail don't care what the content of the payload is. At least that's my understanding.
From: David Empson on 19 Jun 2010 19:31 Mark Conrad <aeiou(a)mostly.invalid> wrote: > Notice when QT plays a HD video, it lists the video > it is playing as MP4. "HD" is not a video format. It is simply an indication that the video is higher definition than a standard television. Typical sizes (intended for wide-screen TV use) are 720p, 1080i and 1080p. The actual video format could be a wide range of things. One of the commonly used formats for HD video is H.264, which can be played in a variety of container formats including MPEG-4, Flash and others. In this case, your HD video happens to be in an MPEG-4 container (and is probably using H.264). When dealing with video files on a computer, there are two main factors involved: 1. The container format or file type, often indicated by the extension on the filename (but the extension might be wrong or missing). 2. The video format used within the container format. This is sometimes called a "codec" (though strictly speaking a "codec" is actually a software component which is responsible for encoding and decoding a particular video format). There are lots of container formats in common use: QuickTime (.mov), MPEG-1 (.mpg or .mpeg), MPEG-2 (.mp2, .mpg, .mpeg or others), MPEG-4 (.mp4, .m4v or many other extensions), Flash Video (.flv), Windows Media Video (.wmv), Matroska (.mkv), AVI (.avi) and lots more. There are also lots of video formats. H.264 is one example of a video format (H.263 and Sorenson 3 are two other examples.) Just knowing the container format (e.g. file extension) does not tell you anything about what video format is used inside the file, though it might restrict the possible options as some container formats only support a limited set of video formats. You generally need to Get Info on a video file (e.g. in QuickTimer Player) to find out what video format is being used inside the file. > Does this mean that QT can not play HD 1080p videos > directly, instead has to convert HD 1080p to MP4 ? No. Your particular HD video happened to be in an MPEG-4 container. > Confusing, at least to a video newbie like me. > > I like sharp video, the "usual" MP4 looks fuzzy to me, > but these "converted" MP4s look noticably sharper. > > MP4 is MP4, right? How can some MP4s look sharper > than others? (mutter, mutter) There are many factors contributing to the quality of a video, including: - Quality of original camera work (focus, lighting, etc.) - Degree of compression used when creating the video, e.g. to keep the file size small enough. - Dimensions of the original video. Enlarging a small image won't magically add back the missing information, despite what TV crime shows might imply. - If the video is converted from one format to another format which uses lossy compression (which is true for most video formats you will encounter outside of professional video editing), there will be a loss of quality. > While I am complaining, why are there so many friggin different > video formats, haven't these idjits ever heard of "KISS" ? Many reasons. 1. Competition and politics. Some companies don't want to use a competitors container format because of political reasons. 2. Intellectual property. There are complex licensing issues around video formats, and some formats may not be available for a particular purpose due to the expense of licensing the format for that use. 3. Some video formats are designed for different uses, such as editing at full quality, efficient playback, or ease of compression. 4. The characteristics of the distribution medium may impose constraints. For example, if digital video is being broadcast it is essential that the playback be able to recover from data corruption in a short time. Error free data transmission cannot be assumed for broadcast (whereas it can be if you are downloading a file). 5. Advances in technology allow newer formats to be developed that require more powerful computers (or hardware support for playback) than was possible a few years ago. Case in point: H.264 is a general purpose format intended for a wide range of applications, but the CPU performance required to play it increases as the video size increases, limiting low performance or older devices to playing small H.264 videos. Older computers may need to use older and less efficiently compressed video formats in order to play reasonable size video. MPEG-2 is an earlier example of a general purpose format, which has been used for digital television broadcast and on DVDs, but it is rarely used for anything larger than standard definition video. H.264 produces much smaller files than MPEG-2 for the same quality and image size. An older Mac (such as a 400 MHz iMac G3) can't play the H.264 video because it can't decode it fast enough without dropping frames, but it can play the MPEG-2 video (e.g. watch a DVD). -- David Empson dempson(a)actrix.gen.nz
From: Warren Oates on 19 Jun 2010 20:27 In article <1jkdqps.7ax79izci1rcN%dempson(a)actrix.gen.nz>, dempson(a)actrix.gen.nz (David Empson) wrote: > "HD" is not a video format. It is simply an indication that the video is > higher definition than a standard television. Typical sizes (intended > for wide-screen TV use) are 720p, 1080i and 1080p. [good stuff snipped] Very nice explanations, David, thanks. Umm, but now can we get back to our mondegreens and "Why Bible John is A Fruitcake?" -- Very old woody beets will never cook tender. -- Fannie Farmer
From: Mark Conrad on 19 Jun 2010 22:16
In article <1jkdqps.7ax79izci1rcN%dempson(a)actrix.gen.nz>, David Empson <dempson(a)actrix.gen.nz> wrote: > There are also lots of video formats. Okay. I guess attempts to keep things simple and standardized are doomed to failure, when it comes to video formats. My question should have been: "What video formats should I use on a modern Mac, if I am interested in viewing the highest quality video possible? " That should limit any answer to 20 or 30 choices. ;-) Presently, I am using a free utility named "MacTubes" with my late model MacBook Pro. (17", all the bells and whistles) MacTubes seems to be doing a fairly credible job of displaying sharp video, along with the QT player built into Mac OS 10.6.4 - - - but as always I worry that perhaps I should investigate other possibly better methods. ( Blue Ray ? ) I am interested in creating/displaying highly detailed video of beating-heart surgery, to/for a bunch of stupid doctors. Stupid about computers, not stupid about surgery. (hopefully) For obvious reasons, I do not want fuzzy images or choppy video. Lots of times these medical people are working in the wild outback of pot-ridden northern California hospitals, away from their usual dedicated high speed lines - - - also fast "glass fiber" lines are still unheard of in this wild west area, in fact we are still using oatmeal boxes and string for most of our local DSL connections. My temporary answer is to first download the real-time video with MacTubes, where the normal DSL download speeds are only about 4 to 6 megabytes per minute, THEN play the video on the doctor's late model MacBook Pro, commonly a 15-incher with 4 to 8 MB of ram. This really slows down the works, risking patient's lives. Bottom line, don't suffer your next heart attack in N. California, 'cause we are barely out of the stone age. Mark- |