[情報] Lagarith is a Loseless Codec

看板AVEncode (影音編碼技術)作者EijiHoba (Feel)時間13年前 (2011/05/31 22:10)推噓0(0推 0噓 5→)

留言5則, 4人參與討論串1/1

號稱說是Loseless video Codec Lagarith is a lossless video codec intended for editing and archiving. It 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. A comparison for various types of video can be found here. 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. 有專業鄉民可以解說嗎？ -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 218.168.4.227