ffmpeg tutorial

ffmpeg structure

libavcodec
libavformat
libavutil
libavfilter
libavdevice
libswresample
libswscale

gcc

compile option ::: g++ -I /usr/local/ffmpeg/include delete_file.cpp -L /usr/local/ffmpeg/lib -lavformat -o delete_file.o g++ -I /usr/local/ffmpeg/include ffmpeg_list_dir.cpp -L /usr/local/ffmpeg/lib -lavformat -lavutil -o ffmpeg_list_dir.o

log system

should include <libavutil/log.h>
api:

log ::: av_log_set_level() av_log()

file delete and rename (api : http://www.ffmpeg.org/doxygen/4.1/avio_8h.html)

access to file system should include <libavformat/avio.h>

file option ::: avpriv_io_delete() avpriv_io_move()

list dir

list dir ::: avio_open_dir() avio_open_dir() avio_open_dir()

read dic api

read dic ::: AVIODirContext : context AVIODirEntry : entry

Some basic struct for ffmpeg:

Basically audio and video are both containers. Each container has many stream that do not cross over with each other. each stream is made by serverl packet and there is one or more frame in each packet.

AVFormatContext : show which container is deal with
AVStream : show which stream is deal with
AVPacket

Basic Steps

demux(解复用) -> get streams -> read packets -> release resources

get meta data of audio and video

apis ::

av_register_all()
avformat_open_input()/ avformat_close_input(); output : AVFormatContext
av_dump_format(); output : meta data

e.g:

compile : g++ -I /usr/local/ffmpeg/include mediainfo.cpp -L /usr/local/ffmpeg/lib -lavutil -lavformat -o mediainfo.o

output::

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from ‘./1.mp4’: Metadata:

major_brand : isom minor_version : 512 compatible_brands: isomiso2avc1mp41 encoder : Lavf59.10.100

Duration: 00:00:08.24, bitrate: N/A Stream #0:0[0x1](und): Video: h264 (avc1 / 0x31637661), none(tv, bt709), 1920x1080, 3618 kb/s, SAR 1:1 DAR 16:9, 30 fps, 30 tbr, 15360 tbn (default)

Metadata: handler_name : ISO Media file produced by Google Inc. vendor_id : [0][0][0][0]

Stream #0:1[0x2](und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, 2 channels, 127 kb/s (default): Metadata: handler_name : ISO Media file produced by Google Inc. vendor_id : [0][0][0][0]

get audio info

api: av_init_packet() av_find_best_stream() av_read_frame() / av_packet_unref()