Libav: A Comprehensive Overview of Multimedia Processing
Explore the world of Libav, a powerful multimedia processing library. Learn about video file formats, audio codecs, containers, and its rich history. Discover the main libraries and tools, and delve into video compression techniques and transcoding operations.
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Presentation Transcript
Libav Libav :
Outline 01 02 Libav What is Libav? Video File Formats Video? Audio? Codec? Container? 03 04 Build Hands on! Build and create library files. Play with Libav 0_hello_world.c 2
01 Libav So what is this? 3
History We want a better API. Suspended FF + (Fast Forward) = We want to support more features. 2000 2015 2021 2011 4
Libraries Main Libraries Libavutil Libavcodec libavdevice Libavfilter Libavforamt Containing functions for simplifying programming. containing multimedia input/output software frameworks. Containing decoders and encoders for audio/video codecs. Containing demuxers and muxers for multimedia container formats. containing media filters. Libswscale Libswresample Performing highly optimized image scaling and color space/pixel format conversion operations. library performing highly optimized audio resampling, rematrixing and sample format conversionoperations 5
Tools Who use them? 6
02 Video File Formats Video? Audio? Codec? Container? 7
Container Just like a box. Container Codec ! ! Codec H.264 + AAC H.264 + AAC Video Containers and Codecs 8
Box Boxes in Boxes in MPEG Boxes Boxes. MPEG- -4 4part 14 (MP4) part 14 (MP4) Boxes Boxes. Container Box Box Container Box: Box: ftyp ( ftyp (File Type Box mp41 mp41 moov mdat (Media Data Box): File Type Box): ): mp42 mp42 moov( (Movie Box Mpeg Mpeg Standard Standard Movie Box): ): mdat (Media Data Box): 9 Many types of boxes.
Codec Compression Technique of h.264 I I- -frames: frames: are the least compressible but don't require other video frames to decode. P P- -frames: frames: can use data from previous frames to decompressand are more compressible than I-frames. B B- -frames: frames:can use both previous and forward frames for data reference to get the highest amount of data compression. I, B and P-frame 10
Operations 1. Transcoding Codec Netflix Codec 11
Operation 2. Transmuxing 12
03 Hands On 13
Commands Configure ./configure --disable-asm--enable-avdevice--enable-doc --disable-programs --disable-shared --enable-static --disable- bzlib --enable-gray --disable-libopenjpeg--disable-iconv--disable-zlib--prefix=./vs2019_build --toolchain=msvc-- arch=x86 --extra-cflags=-MDd--extra-ldflags="/NODEFAULTLIB:libcmt" --enable-debug Make make make j8 j8 14
04 Play with Libav 15
Play With Libav Planar and Non-Planar Audio Planar Planar C2 C2 C1 C1 C1 C2 Non Planar Non- - Planar C2 C1 C2 C1 C1 C2 16
Play With Libav Decode MP2 Procedure AVPacket AVPacket AVFrame AVFrame Parse Parse Decode Decode Parser CodecContext mp2 mp2 Recv Recv Send Send 17
Link Libav in Visual Studio Hackmd https://hackmd.io/@Henry-Zhou/Byc0GT-HF 18
Reference Learn FFmpeg in a hard way vs2017 ffmpeg 4.0.3 Building libav/ffmpeg with MSVC FFmpeg Doxygen Document 19
