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AVC-Intra is a term used byPanasonic to refer to itsprofiles of theH.264/MPEG-4 AVC standard encapsulated inMXF-format files. Among other features, it records video with onlyintra coding, so as to make it possible to edit videos without loss of quality, and makes other simplifications such as making the size of each frame fixed. The original AVC-Intra defines 10-bit 4:2:0 coding at 50 Mbit/s or 10-bit 4:2:2 at 100 Mbit/s for 1080p/i or 720p/i video.[1]
AVC-Intra is available in Panasonic's high definition broadcast products such as theirP2 card equipped broadcast cameras. Panasonic markets its storage products based on the level of AVC-Intra it can sustain.[2][1]
In April 2007,Panasonic announced AVC-Intra codec support. The use of AVC-Intra provides production quality HD video at bit rates more normally associated withelectronic news gathering applications, permitting full resolution, 10-bit field capture of high quality HD imagery in one piece camera-recorders.
Panasonic claims to follow theSMPTE RP 2027–2007[3] recommended practice specification.[4] Analysis by the x264 project has shown that Panasonic does not comply with this specification[5]
AVC-Intra was intended for video professionals who have to store HD digital video for editing and archiving. According to Panasonic, the new technology significantly outperforms the olderHDV (MPEG2 based) andDVCPRO HD (DV based) formats, allowing the codec in certain conditions to maintain better quality in half the storage space of DVCPRO HD.[citation needed]
AVC-Intra defines two classes:
Common to both classes;
Panasonic's implementation of AVC-Intra codec has following limitations: 8 × 8 transform only, 8 × 8 intra prediction only, 10 slices per picture, MBAFF for interlace material, custom quantization matrices for each class and each resolution.[6]
The Panasonic AVC-Ultra family defines an additional three new encoding parameters within theMPEG-4 Part 10 (still H.264) standard, utilizing up to the 4:4:4 Intra Predictive Profile, as well as an additional low bitrate proxy recording mode. AVC-Ultra includes three parts: AVC-Intra, AVC-LongG, and AVC-Proxy.[7][8][9]
AVC-Intra is an expanded version of the existing AVC Intra. Changes include:[9]: 4
AVC-LongG enables "long" (inter frame compression) for vastly increased compression rates[10] at qualities comparable to AVC-Intra. It is intended for reducing operation costs in video production, and especially for transmitting HD video over 50 Mbps communication lines intended for SDTV.[9]: 5 All levels are VBR. There are four levels: G6 (4:2:0 8-bit), G12 (4:2:0 8-bit), G25 (4:2:2 10-bit), G50 (4:2:2 10-bit) with the numbers corresponding to the bitrate at 1080i50/60 and 720p50/60. G6 and G12 support themov format in addition to MXF.[9]: 4
AVC-Proxy uses greatly reduced bitrates. All levels are VBR, 4:2:0 8-bit, and use the QuickTime mov format. The highest level is G6 (6 Mbps for all resolutions, no downscaling). The lower levels, SHQ, HQ, LOW, reduce the input stream's resolution to achieve 3.5, 1.5, and 0.8 Mbps respectively.[9]: 4 A recoder can generate a higher-quality recording and AVC-Proxy at the same time. The smaller "proxy" recording is then useful in reviewing the content or off-line editing in a remote place.[9]: 9
Several companies introduced AVC Intra codecsemiconductor intellectual property cores.[27]