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This article mainly introduces "what are the eight libraries and common functions". In daily operation, I believe many people have doubts about the eight libraries and common functions. The editor consulted all kinds of materials and sorted out simple and easy-to-use operation methods. I hope it will be helpful for you to answer the questions about "what are the eight libraries and common functions?" Next, please follow the editor to study!

Eight libraries

1.libavutil core tool library, one of the most basic modules, other modules will rely on this library to do some basic audio and video processing operations

2. Libavformat file format and protocol library, encapsulating Protocol layer and Demuxer, Muxer layer, making the protocol and format transparent to developers.

3. Libavcodec coding and decoding library, encapsulated with Codec layer, but some codec have their own License, FFmpe will not add libraries such as libx264, FDK-AAC, Lame by default, but FFmpeg wants a platform that can add other third-party codec as plug-ins to provide developers with a unified interface 4.libavfilter audio and video filter library, this module includes audio and video effects processing, in the use of FFmpeg API for coding and decoding process You can use this module to do special effects for audio and video data efficiently.

5. Libavdevice I / O device library, such as ffplay, a tool that needs to be compiled to play sound or video, needs to make sure that the module is open, and colleagues also need to precompile libsdl. The device module uses libsdl library to play sound and video.

6.libswresample is used for audio resampling. It can convert many kinds of basic information such as channel number, data format, sampling rate and so on.

7.libswscale this module is used for image format conversion and can convert YUV data into RGB data.

8.libpostproc this module is used for post-processing. When we use filter, we need to open this module. Filter will use some of the basic functions of this module. Older ffmpeg will also compile the avresamle module, which is also used to resample the original audio, but it has been abandoned. It is recommended to use libswresample instead. In addition, the library can also contain X264 library for H.264/MPEG-4 AVC video coding. Is the most commonly used lossy video encoder, supports CBR and VBR modes, and can directly change the bitrate setting in the coding process, which is very suitable for live streaming scenarios. Can do the function of adaptive code rate.

Common function

Av_register_all (): register all components

2.avformat_open_input (): open the input video file

3.avformat_find_stream_info (): get video file information

4.avcodec_find_decoder (): find the decoder

5.avcodec_open1 (): open the decoder

6.av_read_frame (): reads a frame of compressed data from an input file

7.avcodec_decode_video2 (): decode a frame of compressed data

8.avcodec_close (): turn off the decoder

9.avformat_close_input (): close the input video file

At this point, the study of "what are the eight libraries and common functions" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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