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Scala - Media
Working with multimedia file formats, encoding, etc.
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Jun 25, 2004: File Format Guidelines
InfoChannel supports the following file formats. Graphics- BMP, GIF, IFF, JPEG, PCD, PCX, PNG, Targa, TIFF Video- AVI, QuickTime 3, FLC, MPEG 1 & 2, WMV, Flash Audio- MP3, WAV, MIDI, CD However, some formats work better than others. Here are some recommendations: Backgrounds- JPG for photos and textures, PNG for solid colors and gradients. Tiff (RGB, PC encoded) is supported but PNG compresses slightly better. Foreground Clips: JPG for photos where detail is not critical, PNG for images where clarity is important, and if alpha channel is needed. GIF is supported but not recommended since it's limited to 256 colors. Video: MPEG2 for full-screen videos, MPEG1 for partial-screen clips. For MPEG2 use standard DVD settings (6 mbit, 29.97fps (30 is acceptable too), interlaced). MPEG1 is more flexible. You can use 2-4 mbit bitrate for small file size/low quality or 6-8 for large files/higher quality. Other settings: 30fps, non-interlaced. Sound: MP3 is preferred, but you may need use WAV if you're trying to loop a clip and are hearing a pause between loops. |
Jun 26, 2004: Video Encoding
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Try to start with the best quality source video (of course). Uncompressed is the best, but if you're limited on disk space, you'll have to choose a codec with good compression and minimal quality loss. The highest quality codecs are: AVI - MJPEG, MPEG2, MPEG4, DV (slight color loss) QuickTIme - Animation, Sorenson 3, MPEG 2 or 4 About converting DV to MPEG There is some color loss due to the ways that the two formats store color data. DV is 4.1.1 = luma/b-y color/r-y color. MPEG is 4.2.0 = luma/color b/r alternating by fields/unused. When DV is re-encoded as MPEG the two color channels are merged into one, reducing the quality. This may only be slightly noticeable, but should be considered. PAL DV 4.2.0 and doesn't have this problem. MPEG 2 Settings MPEG2 has "profiles" that are consistent sets of settings. A very commmon selection would be:
DV is 3.5mb/s, so if your source is DV, it doesn't help to encode more than 4 mbps. You can also encode at higher resolutions:
Getting the best quality CBR offers the smoothest, most consistent playback. VBR (2-pass) has higher quality but requires a more powerful system for playback. Make sure to select closed GOP which makes slightly bigger files but is less stress on the decoder. Some encoders/codecs don't support non-standard sizes or bitrates, particularly with MPEG2. MPEG1 offers comparable quality lets you select different resolutions and bitrates. MPEG1 requires the video width and height be evenly divisible by 8. MPEG2 is 16. Using MPEG4 DivX 5.1 DivX is a great format for highly compressed, high quality video. It does require a decent CPU to play back, though. Some good typical settings would be:
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