A: This article specifically covers the video formats used or considered for use up to Amiga Forever 6.0 (released in 2004). Amiga Forever 2005 and higher use industry-standard video DVDs.
The CD Edition of Amiga Forever (before 2005) contained several hours of video footage which had to be "encoded" (compressed) to save disk space while trying to preserve as much visual quality as possible.
The first versions of Amiga Forever used MPEG-1 to encode videos. This technology, released by the Moving Pictures Experts Group (MPEG) of the International Standards Organization (ISO), is also used on Video CDs (VCDs). Some of the advantages of MPEG-1 include:
- Well-defined specification with little or no unsupported variations and few incompatibilities between encoders and decoders (i.e. player software)
- Availability of players on all platforms (Amiga, Windows, Mac, GNU/Linux, Unix, etc.)
- Ideal for playback using average CPUs of 1997, including the Amiga's Motorola 68000 series
- Royalty-free distribution of encoded video files
Since 1997, new encoding specifications and software were released and more powerful CPUs became popular, making it possible to add more video footage to Amiga Forever while at the same time significantly improving the video quality with respect to the previously released MPEG-1 files. Not only did MPEG-2, the successor of MPEG-1, become popular on digital cable and satellite TV, and as the format used on DVDs, but MPEG-4, the successor of MPEG-2, started moving from the labs to real world applications.
Unfortunately, MPEG-4 took much longer than expected both to be finalized and to gain acceptance, while competing technologies were gaining ground. For example, Apple released different versions of its QuickTime video encoding specification and software, and Microsoft did the same with its own Windows Media codecs.
Between 1998 and 1999:
- Microsoft released a new "version 3" Windows Media Player codec based on preliminary MPEG-4 specifications. This codec, like previous MPEG-4 codecs released by Microsoft, only supported MPEG-4 data wrapped in Microsoft's proprietary ASF file and streaming formats.
- The ISO adopted Apple's QuickTime file format (not video compression technology) as a container for MPEG-4 data.
- Jérôme Rota modified Microsoft's preliminary codec, allowing it to play back MPEG-4 videos stored in "normal" files (e.g. AVI) and releasing it as "DivX;-)". This modified codec, which did not have the blessing of either Microsoft or the ISO MPEG-4 committee became unexpectedly popular and also known as "the MP3 for video."
To further clarify some common misunderstandings, when Microsoft states that it was one of the first companies to adopt MPEG-4, this doesn't mean that Windows Media Player as shipped until 2003 can play back, or ever was able to play back, .mp4 video files (because Microsoft only supported MPEG-4 in .asf files or streams). Similarly, when Apple says that the ISO adopted the QuickTime file format, that only refers to the file format (which, like the Amiga's IFF, is a generic "wrapper" or "container"), and not to the video or audio encoding technology used by QuickTime before Apple itself adopted MPEG-4.
During 2002 and 2003, while the MPEG-4 video compression methods such as Simple Profile (SP) and Advanced Simple Profile (ASP) were being embraced by companies like Apple and Real Networks, the ISO was busy working on new MPEG-4 extensions such as H.264 (also known as AVC, or MPEG-4 Part 10). In the meantime, Microsoft released version 9 of the Windows Media encoding technology (WM9), formerly code-named "Corona". The WM9 video decoding technology also goes under the more platform-neutral reference title of VC-1.
The Windows Media 9 video codec, released as a standard by the Society of Motion Picture and Television Engineers under the name of "VC-1" is, according to independent reviews and experts, not only superior in terms of both quality and compression to both ASP and AVC, but it also offers a few other advantages over MPEG-4:
- No major incompatibilities between Microsoft's encoder (Windows Media Encoder) and decoder (Windows Media Player and codecs) software
- Free encoder and decoder software
- No royalties to distribute WM9/VC-1-encoded video files
Until the end of 2003, while there were MPEG-4 players for different computing platforms (e.g. Windows, Mac, GNU/Linux, Amiga), Microsoft had made available its WM9/VC-1-capable codecs for Windows only (the appropriate codec is automatically downloaded when Windows Media Player 7.1 or higher are used). On November 8, 2003, less than a month after Apple released its iTunes music software for Windows, Microsoft released Windows Media Player 9 for Mac OS. In March 2004 the Steering Committee of the DVD Forum, which oversees official DVD formats, gave preliminary approval to VC-1 (in addition to MPEG-4 AVC and MPEG-2) as a codec for use in the HD DVD Video specification, to be implemented on its new 20 GB blue laser DVD media. In September 2004 the Blu-ray Disc Association, which is proposing its BD-ROM specification as an additional possible evolution to the DVD, also endorsed DV-1 as part of its standard.
Unlike Apple, Microsoft decided not to support MPEG-4 video files in its Media Player for Windows, which therefore only supports MPEG-4-encoded movies if a third-party codec is installed. As of early 2004, neither Microsoft nor Apple supported the MPEG-4 AVC profile in their respective players.
In 2009, Microsoft introduced support for MPEG-4 (including the AVC profile) in Windows 7, which has built-in MPEG-4 playback capability.
In spite of technical, usability and economical advantages of Windows Media 9 (superior quality, shorter files, ease of playback under Windows, free encoding software and free redistribution of encoded files), Cloanto originally selected MPEG-4 as the new video format of choice for the Amiga Forever CD-ROM, because of the anticipated superior cross-platform support of MPEG-4 over Windows Media 9 technology. MPEG-2 was bypassed because it offered inferior quality and compression results compared to even the simplest MPEG-4 profiles.
The videos stored on the Amiga Forever 6.0 CD-ROM were to be encoded using the MPEG-4 Advanced Simple Profile (ASP). The ASP codec was chosen instead of AVC (H.264) because of the following reasons:
- Limited support for AVC in encoding software
- Limited support for AVC in decoding software (players)
- AVC playback requires more powerful CPUs than ASP
- The original videos themselves are mostly not better than VHS quality
In practice, once the contracts for the distribution of the videos under an MPEG-4 patent portfolio license had already been signed, it turned out that, even with the latest encoding software versions, in order to create MPEG-4 video files which were compatible with major player applications on different platforms (e.g. Windows Media with DivX or 3ivx codex, QuickTime Player, DivX Player) unexpected quality compromises had to be accepted in order to retain compatibility. This significantly diminished the value of the (theoretical) technological advantage of MPEG-4 over, for example, MPEG-2. The original goal of uncompromising quality with maximum cross-platform compatibility had become a victim of the complexity of MPEG-4 and its partial implementation in different players on various platforms.
Considering the overall situation, it was at that point decided to use the highest quality Windows Media 9 codec options to prepare the Amiga Forever videos for distribution, and to further add a HighMAT data layer which would make the media not only compatible with Windows and Mac versions of Windows Media Player, but also with hardware players. Amiga Forever 6.0 was therefore released with WM9/VC-1 video content, resulting in a picture quality which is even superior to that of MPEG-4 AVC, as tested for possible future use in Amiga Forever.
It is expected that during 2004 and 2005 not only will AVC be better supported, but Microsoft itself may perhaps include MPEG-4 support in its Windows Media Player series. Also, the choice of new codecs for the next-generation DVD standard will in turn influence the acceptance of such codecs.
At Cloanto we hired some of the best professionals and equipment in the video field to digitally preserve the original Amiga video tapes. We are excited that WM9 makes it possible to now release these historical videos in a quality which is almost always better than that which can be achieved with a home VCR playing back 15-year old VHS tapes. We will closely monitor the evolution of video codecs, which keeps surprising even the experts in this field for some of its unexpected innovations, and decide accordingly for the future use of new codecs.
If you would like to share your thoughts on this topic please do not hesitate to let us know.