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MPEG4 Camcorders - ASP vs. AVC, SD vs. HD

September 27, 2007



A couple of years ago the most advanced consumer camcorders could capture only standard definition video (SD) encoding it with MPEG4 ASP codec. So a "MPEG4 camcorder" at that time could do only one thing - record MPEG-4 ASP standard definition video (SD). Much has changed since that time. Some camcorders can now encode video with better MPEG4 AVC (H.264) codecs. There have appeared camcorders that can capture HD (High Definition) video. So it's not enough to just say a "MPEG4 camcorder" - you have to specify video resolution and codec.

So, camcorders can be divided into four groups:

  1. MPEG4 ASP SD
  2. MPEG4 ASP HD
  3. MPEG4 AVC SD
  4. MPEG4 AVC HD

This is not just a matter of different abbreviations, but also of common sense - you should pay close attention to it when you buy a camcorder.

Note that the most advanced MPEG4 AVC HD camcorder won't be the best choice for all users, even if we don't take its high price into account. So it's important to understand pros and cons of each camcorder type. Let's analyze this issue in more detail.

In order to determine which camcorder is your personal best choice, we'll try to answer another series of traditional questions: "What?", "Where?", "When?", and "How much?" Then we'll try to determine target audiences for each class of these camcorders.

"What?" Typical characteristics of camcorders of each group.

"Where?" Devices that can play video, captured by these camcorders.

"When?" Prospects of each camcorder.

"How much?" Your expenses on equipment and video playback.

But let's return to the theory at first.

MPEG-4 ASP and AVC - who is who?

In our previous articles we examined MPEG codecs with interframe compression, their differences from codecs where each frame is compressed - MJPEG and DV. So we'll not repeat ourselves. We'll focus on "interbreed" peculiarities of various MPEG-4 codecs.

MPEG-4 (ISO 14496) is a popular open standard developed by the Moving Picture Experts Group (MPEG), a workgroup of International Organization for Standardization (ISO). The MPEG-4 standard is divided into several substandards, in particular:

  • ISO 14496-1, format of the MP4 file container
  • ISO 14496-2 (Advanced Simple Profile - ASP)
  • ISO 14496-3 (Advanced Audio Coding - AAC)
  • ISO 14496-10 (Advanced Video Coding - AVC), it's also called H.264.

The MPEG-4 ASP group includes widely popular DivX and XviD codecs. MPEG-4 ASP has been used for a long time to record home video. It was so omnipresent that people omit "ASP" when they speak about it.

Consumer video devices have been using a MPEG-4 ASP profile called HTP (Home Theater Profile). As HTP was developed by authors of the DivX codec, it's often called DivX-certificate (do not confuse it with DivX codec).

HTP and DivX certificate are often associated with MPEG-4 ASP. But it's not correct - HTP does not include such video enhancements and bit rate reduction tools as:

  • QPEL (Quarter Pixel Motion Search Precision)
  • GMC (Global Motion Compensation)
  • Besides, frame size in HTP is limited to 576 lines at 25 fps, or 480 lines at 30 fps.

That and similar names (DivX codec and DivX certificate) caused a great deal of terminology confusion here.

The MPEG-4 AVC substandard is one of the latest and most advanced video encoding formats. It has appeared relatively recently, only in 2003, as a result of cooperation between MPEG (Moving Pictures Experts Group) and VCEG (Video Coding Experts Group). This standard is called MPEG-4 Part 10 (AVC) by MPEG; VCEG calls it H.264 (by the number of the ITU document). Hence two names.

Just like MPEG-4 ASP, MPEG-4 AVC determines profiles:

  • Baseline
  • Main
  • Extended
  • Several High profiles

It's too early to say which profile will become more popular, because MPEG-4 AVC has been released only recently.

Unlike MPEG-4 ASP, MPEG-4 AVC offers more powerful tools to enhance video quality and reduce bit rates. In particular, they are CAVLC/CABAC lossless compression methods, variable block size (ASP block size is fixed), multiple reference frames, not just I/P/B-frames like in ASP RDO optimizations to decrease distortions, etc.

All these features help MPEG-4 AVC codecs consume bit rates much more efficiently, thus achieving higher video quality.
The reverse of the medal is higher requirements to MPEG-4 AVC video recording/playback devices.

For example, even an old 1 GHz Pentium-III or Celeron can cope with playing MPEG-4 ASP 640x480 30fps video, but MPEG-4 AVC can be a hard task even for the top Pentium IV. This processor may not cope with AVC HD (High Definition)! Such high requirements of MPEG-4 AVC make it difficult to design stand-alone players, although they are already appearing in the market.

Standard Definition and High Definition video players

SD Video (Standard Definition Video) can be described with the word "usual". A usual TV set, a usual VHS tape recorder, a usual DVD player connected with a usual Composite or S-Video cable to usual SCART - that's a usual Standard Definition video system. Standard Definition limits video to 576 lines at 25 fps, or 480 lines at 30 fps*.

* Note: As recording and transmitting analog signals with 576 lines at 25 fps historically has to do with PAL, and 480 lines at 30 fps - with NTSC, these names are often used to denote digital recordings of these resolutions, although it's not correct from the technical point of view.





Standard Definition Video had appeared and developed in parallel with television, so practically all consumer electronics to record, store, play, and display video meet its requirements by definition.

Note that Composite and S-Video can transmit only Standard Definition video signal, while Component, D-Sub (VGA), and DVI/HDMI can also work with High Definition video.

Most modern DVD players (including DVD MPEG4 players) can work only with SD video discs. Even if this player is equipped with HDMI or Component interfaces, it still plays SD video* (in contempt of advertisements about "playing usual DVDs with HD resolution").

* Note: If a "usual" DVD player is connected to a digital LCD or PDP HD TV set, original SD must be scaled up to HD resolution of the TV set somewhere. If you use an SD interface, it will be done in a TV set. In case of an HD interface, it will be done in a player. That's all the difference! In this case you should choose a connection, which could provide higher video quality in a given video system.

The number of vertical lines is not fixed in SD Video. If we speak of analog methods, it depends mostly on a frequency band. For example, an analog method of recording SD VHS video signal provides lower resolution than wider-band S-VHS. Composite interface offers lower resolution than S-Video, and so forth*.

* Note: you shouldn't mix up video recording, storage, transmission, and displaying. These notions are subject to different standards and do not match in a general case. Resolution of the entire video section from recording to displaying will be limited by the worst device in the path. For example, when you connect a VHS tape recorder to a TV set through S-Video, you will not get as crisp image as you can by connecting a DVD player. VHS is a restraint here. But if you watch Video CD on this DVD player, the resolution will drop because of the recording on a disc. Resolution will not be maximal, if you watch DVD on a TV set connected to a player via Composite, etc...

What concerns digital video, vertical resolution is determined by a standard.

"Holy Wars" have been raging for decades: PAL versus NTSC, progressive versus interlaced. We'll not focus on this issue now.

The notion of HD Video (High Definition Video) is much younger. This notion includes High Definition Video proper and corresponding players and displays with resolutions starting from 720 lines (HD Ready*), to 1080 lines (Full HD**).

* Note: some vendors take undue freedoms with the word "Ready" and use this label for devices that can only receive HD signal (for example, via HDMI), but display it with a standard resolution. For example, many inexpensive plasma panels come with a 848x480 panel. So they cannot be HD Ready, even if they are equipped with HDMI-In.

** Note: Displays with vertical lines slightly above 1000 (for example, 1024x1080) are not Full HD devices.



Let's dwell on HD video players. They are Blu-Ray and HD DVD players in the first place, they can work with high-capacity media. But they are not wide-spread yet (some understatement :-\ ) and very expensive (both players and discs). The majority of usual DVD players (with/without MPEG-4 support) are not High Definition devices, even if they can output HD signal to the HDMI interface. But there are some players that can play HD video recorded on usual DVDs. For example, XORO HSD 8500 (it can play HD MPEG2 and MPEG4 ASP video) and KISS 1600 (it can also play MPEG4 AVC HD video). To differentiate them from HD DVD players, we'll call them "DVD with HD support".

The rule of the worst element in a chain determining the resulting video quality is even more important for HD video. A DVD player with HD support must be connected to an HD display via a properly configured HD-compliant interface. Only in this case an HD recording will be displayed with high definition!

So we have found out that MPEG4 AVC video generally provides higher video quality than MPEG4 ASP, and High Definition Video provides higher definition than Standard Definition. On the other hand, you can watch MPEG4 ASP SD on any TV set with any DVD MPEG4 player, while other video standards have higher hardware requirements.

Let's analyze our four groups of camcorders from this point of view.

MPEG4 ASP SD camcorders

The oldest type of camcorders that encode video into MPEG4. Such video can be captured not only by camcorders, but also by many photo (photo/video) devices from Casio, Pentax, Samsung, Sanyo, Kodak and others, as well as by some advanced camera phones (for example, Nokia N93 and some others).





It's simple.

"What?" These camcorders provide the lowest video quality among our four groups of products. Depending on a device and shooting conditions, a video record may be on the level of "average" VHS or a cheap miniDV camcorder at best.

"Where?" It's simple. You can easily repack recorded video into the AVI container (you can read how to do it in our articles "Processing MPEG4 recordings step by step" and "Processing MPEG4 recordings step by step. Part II") and burn them to CD or DVD. Such a disc can be played by any MPEG4 DVD player on any TV set. Unlike its direct competitor (DVD camcorders), MPEG4 ASP SD camcorders can not only burn recorded video, they also allow their users to edit it.

"When?" "Yesterday" (several years ago). "Today" (with some reserve). "Tomorrow", in a couple of years, such video will look old-fashioned compared to HD and AVC.

"How much?" Cheap. It's currently the most affordable technical solution among all the groups we review today. You will just need such a camcorder (it's inexpensive) and any more-or-less modern MPEG4 HTP DVD player. What concerns a "usual" TV set, they are extremely widespread.

Thus, if you need a cheap compact camcorder to record video of relatively high quality and then easily edit it, assemble and burn a video disc, which can be played on any DivX-compatible MPEG4 DVD player, you may have a closer look at one of such products.

MPEG4 ASP HD camcorders

They appeared on the market much later than the previous group. There are currently only several Sanyo Xacti HD devices and some Kodak cameras of this type.



"What?" Video definition is up to the mark here. But problems with video quality are actually the same. If you try to compare it to miniDV camcorders, much depends on shooting and playback conditions. A good MPEG4 ASP HD record on an HD TV will look better than SD video captured with a miniDV camcorder owing to higher resolution. If you watch it on a usual TV set, miniDV will certainly look better - it uses SD features hundred-per-cent, and the advantage of MPEG4 ASP HD will be lost, but MPEG artifacts will remain. If shooting environments are far from perfect (insufficient light, dynamic scenes), typical MPEG4 ASP artifacts will spoil your impression of such a camcorder even on the HD TV.

"Where?" To view video recorded with such a device, you will need at least an HD Ready TV set connected via HD interface to a DVD with HD support. You can also connect a computer to an HD TV set via the HD interface, or play video on a good monitor, which is less comfortable.

"When?" If you have an HD TV set, it will be "today". What concerns "tomorrow", it's a complex issue. It all depends on whether most AVC HD players will support ASP HD as well. Of course, ASP HD video can always be converted to AVC HD. But it's not the best option... So we can say the following - if you really want it, ASP HD is "HD for today". ASP HD camcorders record good HD video, and they require less expenses on equipment and hardware.

"How much?" If you have an HD TV set, you will have to buy only a camcorder (it's approximately 1.5 times as expensive as ASP SD products) and a DVD-MPEG4 player with HD video support. There are not many players of this kind so far, but their price is similar to that of top DVD players without HD support. Thus, such a solution will be cheaper now than the most advanced MPEG4 AVC HD camcorders.

However, if you are only planning on buying an HD TV set, your expenses will be much higher, and you should think twice whether you should buy such a camcorder now or content yourself with an SD camcorder (ASP or AVC - we'll speak about this choice below). In this case you may put off your purchase of an HD camcorder until you buy such a TV set - better MPEG4 AVC HD devices may become affordable by that time.

MPEG4 AVC SD camcorders

The first camcorders of that type have just appeared. There are only several products of this kind from Casio and Sanyo, plus a few product announcements.



"What?" The answer is simple again. Video quality is similar to a Mid-End miniDV camcorder. Video is recorded in a compressed format, so there is no need to transcode as you edit your video. Advantages of these devices include no need for tapes, compact dimensions, as well as higher video quality compared to ASP.
Some of these camcorders can capture 848x480 video that plays nicely on wide SD TV sets.

"Where?" Any TV set will do for this video. What concerns a player, the situation is much more complex. However, if you plan on transcoding your video into usual DVDs, there will be no problems with a player. But you will lose the above mentioned advantage over miniDV camcorders. Theoretically, you can cut a movie without transcoding, for your future player, so to speak, and transcode the movie into MPEG2 or MPEG4 ASP for a "temporary" disc.

"When?" "Today". But you will have to solve problems with playback and transcoding. If you are not going to buy an HD TV set in the nearest future, the answer is "tomorrow". At least if you plan on buying a miniDV camcorder now, pay closer attention to MPEG4 AVC SD products. They may be a better choice for your needs.

"How much?" MPEG4 AVC SD camcorders are not much more expensive than MPEG4 ASP SD devices of the same class. There are no special requirements to a TV set. If it were not for a player... However, if you are not discouraged by transcoding video, the price of this solution will be actually on the level of MPEG4 ASP SD. It will take much time to transcode video, of course. But video quality will be higher than in the first case, even despite transcoding losses.

There will soon appear DVD players for MPEG4 AVC SD video, but they will most likely support MPEG4 AVC HD as well. If you still have an SD TV set, the difference from HD video will not be large. However, if you have an HD TV set, this type of camcorders is certainly outscored.

MPEG4 AVC HD camcorders

It's the latest most interesting and promising type of all camcorder groups we review today. However, there are reefs here as well. Firstly, there's just a few players that support this video format. Secondly, there were very few devices of this type available in stores, when I wrote this article, even though there were a lot of announcements.



"What?" Video quality and definition are the highest among all camcorder groups reviewed today. They are much higher than those of most consumer camcorders can currently offer. There will be cheaper and more expensive products, of course. But video quality will be determined by lenses and other parameters, it won't be limited by the codec, as it happens in the other camcorder types.

"Where?" Such video will require either a powerful computer (not all P-IV processors can cope with this task), or a Blu-Ray / HD DVD player, or a "usual" DVD with AVC HD support. Besides, you will need an HD Ready or Full HD TV set connected to the player via the HD interface.

"When?" "Today" is possible, but it's not that easy. "Tomorrow" and "the day after tomorrow" for sure. We can see no real competitors in the nearest future.

"How much?" One word - "expensive"... To be more exact, "very expensive". It's the most expensive solution not only among all options reviewed in this article, but also among other consumer products. An expensive camcorder, an expensive computer for video processing, an expensive player, and a very expensive TV set...

These solutions will certainly become cheaper in time. If you have an HD TV set, or plan on buying it, this solution becomes attractive in the nearest future. However, if you want to shoot video now, which will look good even in future (to shoot video for keepsville, so to speak) no matter the cost, you can think about buying such a camcorder even today.

Conclusion

Let's lay down some conclusions:

  1. MPEG4 ASP SD camcorder: the most inexpensive solution. It allows to easily cut and record a ready (and relatively good) movie, which can be played with a popular MPEG4 HTP DVD player on any TV set. It may be interesting for a beginner, or if you are pressed for money, or as an inexpensive and compact "backup solution"
  2. MPEG4 ASP HD camcorder: it may be an interesting solution for those who want to play with High Definition video, but who are not ready to pay for a more expensive solution with a MPEG4 AVC HD camcorder
  3. MPEG4 AVC SD camcorder: it may be a good choice, if you are not satisfied with MPEG4 ASP SD quality, but you don't want to buy an HD TV set in the nearest future, and want a more compact "tapeless" alternative to MiniDV, and you have nothing against transcoding video
  4. MPEG4 AVC HD camcorder: it's your choice, if compromise is not for you, if you are ready to pay much for your choice, if you want to play your movies on a large HD screen, and if you don't want your videos to look old-fashioned in future.

These are general recommendations, of course. You may find other arguments for this or that solution. But we hope that our attempt to analyze the current situation in the market of MPEG4 camcorders will help our readers make a well-considered choice.

Dmitry Dorofeyev aka DMITRY (dmitrydor@ixbt.com)
Oleg Mikheyev aka Gray Wolf (graywolf2004@mail.ru)
September 27, 2007

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