Lagarith 0 votes

Lossless Video Codec

Lagarith is a lossless video codec intended for editing and archiving. Lagarith offers better compression than codecs like Huffyuv, Alparysoft, and CorePNG. There are a few lossless codecs that can compress better than Lagarith, such as MSU and FFV1; however Lagarith tends to be faster than these codecs. Lagarith is able to operate in several colorspaces - RGB24, RGB32, RGBA, YUY2, and YV12. For DVD video, the compression is typically only 10-30% better than Huffyuv. However, for high static scenes or highly compressible scenes, Lagarith significantly outperforms Huffyuv. Lagarith is able to outperform Huffyuv due to the fact that it uses a much better compression method. Pixel values are first predicted using median prediction (the same method used when “Predict Median” is selected in Huffyuv). This results in a much more compressible data stream. In Huffyuv, this byte stream would then be compress using Huffman compression. In Lagarith, the byte stream may be subjected to a modified Run Length Encoding if it will result in better compression. The resulting byte stream from that is then compressed using Arithmetic compression, which, unlike Huffman compression, can use fractional bits per symbol. This allows the compressed size to be very close to the entropy of the data, and is why Lagarith can compress simple frames much better than Huffyuv, and avoid expanding high static video. Additionally, Lagarith has support for null frames; if the previous frame is mathematically identical to the current, the current frame is discarded and the decoder will simply use the previous frame again.

The trade-off for this improved compression is speed. On a single processor system, Lagarith can be significantly slower than Huffyuv on typical video. Additionally, the decode speed tends to be slower than the encode speed; this is due to the nature of Arithmetic compression and the prediction algorithm. Fortunately, for the situations where the codec offers the most advantages over Huffyuv, the speed difference between the two tends to decrease, and Lagarith can be much faster for simple video. For multiple processor systems, Lagarith 1.3.0 can take advantage of additional processors; while Huffyuv cannot. On such systems Lagarith may be faster than Huffyuv.

This codec was build using the Huffyuv source as a template, and uses some Huffyuv code, most notably the routine to upsample YUY2 video to RGB and to perform pixel prediction on YUY2 video. Other colorspace conversion routines were taken from AviSynth. Lagarith is released under the GPL.

Huffyuv 0 votes

Huffyuv (or HuffYUV) is a lossless video codec created by Ben Rudiak-Gould which is meant to replace uncompressed YCbCr as a video capture format.

Despite the “YUV” in the name, it does not compress the YUV color space, but YCbCr.[citation needed] The codec can also compress in the RGB color space.

“Lossless” means that the output from the decompressor is bit-for-bit identical with the original input to the compressor. Lossless only occurs when the compression color space matches the input and output color space. When the color spaces do not match, a low loss compression is performed.

Huffyuv's algorithm is similar to that of lossless JPEG, in that it predicts each sample and then Huffman-encodes the error.

Dirac 0 votes

Video Compression

Dirac is an open and royalty-free video compression format, specification and system developed by BBC Research at the BBC. Schrödinger and dirac-research (formerly just called 'Dirac') are open and royalty-free software implementations (video codecs) of Dirac. Dirac format aims to provide high-quality video compression for Ultra HDTV and beyond, and as such competes with existing formats such as H.264 and VC-1.

The specification was finalised in January 2008, and further developments are only bug fixes and constraints. In September of that year, version 1.0.0 of an I-frame only subset known as Dirac Pro was released and has since been standardised by the SMPTE as VC-2. Version 2.2.3 of the full Dirac specification, including motion compensation and inter-frame coding, was issued a few days later. Dirac Pro was used internally by the BBC to transmit HDTV pictures at the Beijing Olympics in 2008.

The format implementations are named in honour of the theoretical physicists Paul Dirac and Erwin Schrödinger, who shared the 1933 Nobel Prize in physics.

LAME 0 votes

LAME is a high quality MPEG Audio Layer III (MP3) encoder licensed under the LGPL.

Following the great history of GNU naming, LAME originally stood for LAME Ain't an Mp3 Encoder. LAME started life as a GPL'd patch against the dist10 ISO demonstration source, and thus was incapable of producing an mp3 stream or even being compiled by itself. But in May 2000, the last remnants of the ISO source code were replaced, and now LAME is the source code for a fully LGPL'd MP3 encoder, with speed and quality to rival and often surpass all commercial competitors.

LAME is an educational tool to be used for learning about MP3 encoding. The goal of the LAME project is to use the open source model to improve the psycho acoustics, noise shaping and speed of MP3. LAME is not for everyone - it is distributed as source code only and requires the ability to use a C compiler. However, many popular ripping and encoding programs include the LAME encoding engine, see: Software which uses LAME.

internet Speech Audio Codec(ISAC) 0 votes

internet Speech Audio Codec (iSAC) is a wideband speech codec, developed by Global IP Solutions (GIPS) (acquired by Google Inc in 2011). It is suitable for VoIP applications and streaming audio. The encoded blocks have to be encapsulated in a suitable protocol for transport, eg. RTP.

It is one of the codecs used by AIM Triton, the Gizmo5, QQ, and Google Talk. It was formerly a proprietary codec licensed by Global IP Solutions. As of June 2011, it is part of open source WebRTC project, which includes a royalty-free license for iSAC when using the WebRTC codebase.