FFmpeg转封装（3）

FLV在FFmpeg中的Muxer

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查看FLV文件的Muxer信息

ffmpeg -h muxer=flv

ffmpeg version 4.1 Copyright (c) 2000-2018 the FFmpeg developers
  built with Apple LLVM version 10.0.0 (clang-1000.11.45.5)
  configuration: 
  libavutil      56. 22.100 / 56. 22.100
  libavcodec     58. 35.100 / 58. 35.100
  libavformat    58. 20.100 / 58. 20.100
  libavdevice    58.  5.100 / 58.  5.100
  libavfilter     7. 40.101 /  7. 40.101
  libswscale      5.  3.100 /  5.  3.100
  libswresample   3.  3.100 /  3.  3.100
Muxer flv [FLV (Flash Video)]:
    Common extensions: flv.
    Mime type: video/x-flv.
    Default video codec: flv1.
    Default audio codec: adpcm_swf.
flv muxer AVOptions:
  -flvflags          <flags>      E........ FLV muxer flags (default 0)
     aac_seq_header_detect              E........ Put AAC sequence header based on stream data
     no_sequence_end              E........ disable sequence end for FLV
     no_metadata                  E........ disable metadata for FLV
     no_duration_filesize              E........ disable duration and filesize zero value metadata for FLV
     add_keyframe_index              E........ Add keyframe index metadata

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转FLV

ffmpeg -i 111.mp4 -c copy -f flv 333.flv

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生成带关键索引的FLV

ffmpeg -i 111.mp4 -c copy -f flv -flvflags add_keyframe_index 333.flv

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ffprobe解析FLV文件并显示关键帧索引信息

ffprobe -v trace -i 333.flv

Format flv probed with size=2048 and score=100
[flv @ 0x7ffc1e005800] Before avformat_find_stream_info() pos: 13 bytes read:32768 seeks:0 nb_streams:0
[flv @ 0x7ffc1e005800] type:18, size:1472, last:-1, dts:0 pos:21
[flv @ 0x7ffc1e005800] keyframe stream hasn't been created
[flv @ 0x7ffc1e005800] type:9, size:44, last:-1, dts:0 pos:1508
[flv @ 0x7ffc1e005800] keyframe filepositions = 1578 times = 0
[flv @ 0x7ffc1e005800] keyframe filepositions = 503328 times = 2000
[flv @ 0x7ffc1e005800] keyframe filepositions = 1023475 times = 4000
[flv @ 0x7ffc1e005800] keyframe filepositions = 1534963 times = 6000
[flv @ 0x7ffc1e005800] keyframe filepositions = 2053120 times = 8000
[flv @ 0x7ffc1e005800] keyframe filepositions = 2563198 times = 10000
[flv @ 0x7ffc1e005800] keyframe filepositions = 3083556 times = 12000
[flv @ 0x7ffc1e005800] keyframe filepositions = 3588086 times = 14000
[flv @ 0x7ffc1e005800] keyframe filepositions = 4092655 times = 16000

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