ffmpeg

FFMpeg#

  • FFmpeg/FFmpeg

    • libavcodec 提供大量的编码实现
    • libavformat 实现流体协议,容器格式和基本的 IO 访问
    • libavutil 提供哈希, 解压等其他辅助工具
    • libavfilter 提供一系列过滤器用于修改编码的视频音频
    • libavdevice 提供设备捕捉和重播的访问抽象
    • libswresample 实现音频混合和重新取样
    • libswscale 实现颜色转换和缩放
  • 工具

    • ffmpeg 命令行工具用于操作转换和流媒内容
    • ffplay 多媒体播放器
    • ffprobe 多媒体内容分析工具
    • ffserver 多媒体流体服务器用于实时广播
    • 其他的一些小工具例如 aviocat, ismindex 和 qt-faststart 等

Tips#

  • 常用参数
    • -r 17 修改帧率
    • -an 移除所有音频, -vn 同理
    • -acodec copy 直接复制内容,用户修改容器格式时, -acodec copy 同理
    • -s 324x576 修改大小
    • -vcodec h264 -profile:v high -level 4.2
      • iOS iPhone 5s 后兼容的最高 h264 压缩 来源
      • 查看 h264 相关信息 ffmpeg -h encoder=libx264
    • -movflags +faststart
      • 将部分信息添加到开头,以保证在 web 中未下载完成时也能播放
    • -c:v libx265 -preset medium
      • h265 压缩更好,但是目前设备支持有限
      • -x265-params 查看可行参数
    • -threads
      • 0 优化选择
      • 线程数
      • 多线程需要取决于编码器是否支持
  • 参考
# 安装
# macOS
brew install ffmpeg
# 显示进度
pv input.avi | ffmpeg -i pipe:0 -v warning {arguments}
# 查看支持的像素格式
ffmpeg -pix_fmts
# 查看编码选项
ffmpeg -h encoder=libvpx
# 缩放
# ========
# https://trac.ffmpeg.org/wiki/Scaling
ffmpeg -i input.jpg -vf scale=iw*.5:ih*.5 input_half.png
# 保持比例
ffmpeg -i input.jpg -vf scale=w=320:h=240:force_original_aspect_ratio=decrease output_320.png
# 可以使用 ffplay 预览
ffplay -i input.mp4 -vf scale=iw*.2:ih*.2
# 剪切
# ========
# -ss 开始时间 -t 持续时间 -to 到达时间
ffmpeg -i input.wmv -ss 00:00:30.0 -c copy -t 00:00:10.0 output.wmv
ffmpeg -i input.wmv -ss 30 -c copy -t 10 output.wmv
# -ss 30 -t 10 等同于 -ss 30 -to 40
ffmpeg -i input.wmv -ss 30 -c copy -to 40 output.wmv
# 裁剪
# ========
# https://ffmpeg.org/ffmpeg-filters.html#crop
ffmpeg -i in.mp4 -filter:v "crop=out_w:out_h:x:y" out.mp4
# 使用 ffplay 预览
ffplay -i input.mp4 -vf "crop=in_w:in_h-40"
# 合并拆分
# 将音频重新编码为 aac
ffmpeg -i video.mp4 -i audio.wav -c:v copy -c:a aac -strict experimental output.mp4
# 不对其进行编码
ffmpeg -i video.mp4 -i audio.wav -c copy output.mkv
# 替换音频流
ffmpeg -i video.mp4 -i audio.wav -c:v copy -c:a aac -strict experimental -map 0:v:0 -map 1:a:0 output.mp4
# 分离
ffmpeg -i input.mkv -vn -c:a copy marryme.ogg

编码#

# x264
# ==========
# https://trac.ffmpeg.org/wiki/Encode/H.264
# how to generate dashif compatible mpd files using mp4box https://github.com/Dash-Industry-Forum/dash.js/issues/127
# http://ffmpeg.org/ffmpeg-codecs.html#libx264_002c-libx264rgb
# Note: -strict experimental (or -strict -2) was previously required for this encoder, but it is ​no longer experimental and these options are unnecessary since 5 December 2015.
ffmpeg -h encoder=libx264
pv in.mp4 | ffmpeg -v warning -y -i pipe:0 -vcodec h264 -vf scale=hd480 -acodec aac 480.mp4
# x265
# ==========
# https://trac.ffmpeg.org/wiki/Encode/H.265
# http://x265.readthedocs.io/en/default/
# preset: ultrafast, superfast, veryfast, faster, fast, medium, slow, slower, veryslow, placebo
ffmpeg -i input -c:v libx265 -preset medium -crf 28 -c:a aac -b:a 128k output.mp4
# HLS - HTTP Live Streaming
# ==========
# https://github.com/video-dev/hls.js/
# https://www.vidbeo.com/blog/hls-vs-dash
# https://ffmpeg.org/ffmpeg-formats.html#segment_002c-stream_005fsegment_002c-ssegment
# 如果 ts 不支持的格式
ffmpeg -i input.mp4 \
-c:v mpeg2video -qscale:v 2 \
-c:a mp2 -b:a 192k \
output.ts
# 如果 ts 格式支持
ffmpeg -re -i input.mp4 \
-codec copy -map 0 \
-f segment -segment_list playlist.m3u8 \
-segment_list_flags +live -segment_time 10 \
out%03d.ts
# HLS
# http://ffmpeg.org/ffmpeg-all.html#hls-2
ffmpeg -i input.mp4 -profile:v baseline -level 3.0 -s 640x360 -start_number 0 -hls_time 10 -hls_list_size 0 -f hls index.m3u8
# https://docs.peer5.com/guides/production-ready-hls-vod/
# 单个码率
# 文件结构
# raw.mp4 480.m3u8 480/*.ts
# mkdir 360 480 720 1080
ffmpeg -hide_banner -y -i raw.mp4 \
-vf scale=w=842:h=480:force_original_aspect_ratio=decrease -c:a aac -ar 48000 -c:v h264 -profile:v main -crf 20 -sc_threshold 0 -g 48 -keyint_min 48 -hls_time 4 -hls_playlist_type vod -b:v 1400k -maxrate 1498k -bufsize 2100k -b:a 128k -hls_base_url 480/ -hls_segment_filename 480/%03d.ts 480.m3u8
ffmpeg -hide_banner -y -i raw.mp4 \
-vf scale=w=1280:h=720:force_original_aspect_ratio=decrease -c:a aac -ar 48000 -c:v h264 -profile:v main -crf 20 -sc_threshold 0 -g 48 -keyint_min 48 -hls_time 4 -hls_playlist_type vod -b:v 2800k -maxrate 2996k -bufsize 4200k -b:a 128k -hls_base_url 720/ -hls_segment_filename 720/%03d.ts 720.m3u8
ffmpeg -hide_banner -y -i raw.mp4 \
-vf scale=w=1920:h=1080:force_original_aspect_ratio=decrease -c:a aac -ar 48000 -c:v h264 -profile:v main -crf 20 -sc_threshold 0 -g 48 -keyint_min 48 -hls_time 4 -hls_playlist_type vod -b:v 5000k -maxrate 5350k -bufsize 7500k -b:a 192k -hls_base_url 1080/ -hls_segment_filename 1080/%03d.ts 1080.m3u8
ffmpeg -hide_banner -y -i raw.mp4 \
-vf scale=w=1920:h=1080:force_original_aspect_ratio=decrease -c:a aac -ar 48000 -c:v h264 -profile:v main -crf 20 -sc_threshold 0 -g 48 -b:v 5000k -maxrate 5350k -bufsize 7500k -b:a 192k 1080.mp4
# 多码率
ffmpeg -hide_banner -y -i beach.mkv \
-vf scale=w=640:h=360:force_original_aspect_ratio=decrease -c:a aac -ar 48000 -c:v h264 -profile:v main -crf 20 -sc_threshold 0 -g 48 -keyint_min 48 -hls_time 4 -hls_playlist_type vod -b:v 800k -maxrate 856k -bufsize 1200k -b:a 96k -hls_base_url 360/ -hls_segment_filename 360/%03d.ts 360.m3u8 \
-vf scale=w=842:h=480:force_original_aspect_ratio=decrease -c:a aac -ar 48000 -c:v h264 -profile:v main -crf 20 -sc_threshold 0 -g 48 -keyint_min 48 -hls_time 4 -hls_playlist_type vod -b:v 1400k -maxrate 1498k -bufsize 2100k -b:a 128k -hls_base_url 480/ -hls_segment_filename 480/%03d.ts 480.m3u8 \
-vf scale=w=1280:h=720:force_original_aspect_ratio=decrease -c:a aac -ar 48000 -c:v h264 -profile:v main -crf 20 -sc_threshold 0 -g 48 -keyint_min 48 -hls_time 4 -hls_playlist_type vod -b:v 2800k -maxrate 2996k -bufsize 4200k -b:a 128k -hls_base_url 720/ -hls_segment_filename 720/%03d.ts 720.m3u8 \
-vf scale=w=1920:h=1080:force_original_aspect_ratio=decrease -c:a aac -ar 48000 -c:v h264 -profile:v main -crf 20 -sc_threshold 0 -g 48 -keyint_min 48 -hls_time 4 -hls_playlist_type vod -b:v 5000k -maxrate 5350k -bufsize 7500k -b:a 192k -hls_base_url 1080/ -hls_segment_filename 1080/%03d.ts 1080.m3u8
# 针对不同分辨率做不同的片段
# http://ffmpeg.org/ffmpeg-all.html#segment_002c-stream_005fsegment_002c-ssegment
mkdir -p 1080 720 480
ffmpeg -re -i 1080.mp4 \
-codec copy -map 0 \
-f segment -segment_list 1080.m3u8 \
-segment_list_flags +live -segment_time 10 \
-segment_list_entry_prefix 1080/ \
1080/%03d.ts
ffmpeg -re -i 720.mp4 \
-codec copy -map 0 \
-f segment -segment_list 720.m3u8 \
-segment_list_flags +live -segment_time 10 \
-segment_list_entry_prefix 720/ \
720/%03d.ts
ffmpeg -re -i 480.mp4 \
-codec copy -map 0 \
-f segment -segment_list 480.m3u8 \
-segment_list_flags +live -segment_time 10 \
-segment_list_entry_prefix 480/ \
480/%03d.ts
# m3u8 添加前缀
sed -re 's$^[0-9]$1080/\0$' -i 1080.m3u8
sed -re 's$^[0-9]$720/\0$' -i 720.m3u8
sed -re 's$^[0-9]$480/\0$' -i 480.m3u8
# DASH
# ==========
# dash-avc264 command lines https://gist.github.com/ddennedy/16b7d0c15843829b4dc4
# https://en.wikipedia.org/wiki/Dynamic_Adaptive_Streaming_over_HTTP
# Video dash js multiple resolutions https://github.com/Dash-Industry-Forum/dash.js/issues/1647
pv in.mp4 | ffmpeg -v warning -y -i pipe:0 -vcodec libx264 -profile:v baseline -level 13 -b:v 2000k -vf scale=hd480 -acodec aac -ar 44100 -ac 1 480.mp4
ffmpeg -codec:a libvo_aacenc -ar 44100 -ac 1 -codec:v libx264 -profile:v baseline -level 13 -b:v 2000k output.mp4 -i test.mp4
MP4Box -dash 10000 -dash-profile live -segment-name output-seg output.mp4
MP4Box -dash 10000 -dash-profile live -segment-name 480/seg 480.mp4
MP4Box -h dash
# Streaming
# ==========
# http://trac.ffmpeg.org/wiki/StreamingGuide
# Gif
# ==========
ffmpeg -i in.mov -s 600x400 -pix_fmt rgb24 -r 10 -f gif - | gifsicle --optimize=3 --delay=3 > out.gif
# keep scale
ffmpeg -i in.mov -pix_fmt rgb24 -r 18 -f gif - | gifsicle --optimize=3 --delay=3 > out.gif
# Web Media
# ========
pv in.mp4 | ffmpeg -v warning -y -i pipe:0 -vcodec h264 -vf scale=576:-1 -acodec aac output3.mp4

视频录制#

# 视频捕捉
# https://trac.ffmpeg.org/wiki/Capture/Webcam
# https://trac.ffmpeg.org/wiki/Capture/Desktop
# 查看可使用设备和捕捉
# Windows
# vfwcap 已经被替换为 dshow
ffmpeg -y -f dshow -i list
ffmpeg -y -f dshow -r 25 -i 0 out.mp4
ffmpeg -f dshow -list_devices true -i dummy
ffmpeg -f dshow -list_optione true -i dummy
# Linux
# video4linux2 可简写为 v4l2
# 可使用 x11grab 抓取桌面
ffmpeg -f v4l2 -list_formats all -i /dev/video0
ffmpeg -f v4l2 -framerate 25 -video_size 640x480 -i /dev/video0 output.mkv
# 也可以使用 v4l2 来查看
v4l2-ctl --list-devices
# 查看可控制的参数, 对比度,焦点,缩放等
v4l2-ctl -L
# 修改参数
v4l2-ctl -c <option>=<value>
# OS X
# 主要使用 avfoundation 来操作
ffmpeg -f avfoundation -list_devices true -i ""
ffmpeg -f avfoundation -i "" out.mpg
# 输入设备也可以指定 default,或名字例如 "Integrated" 或者设备索引例如 0
ffmpeg -f avfoundation -i "default" out.mpg
ffmpeg -f avfoundation -i "Integrated" out.mpg
ffmpeg -f avfoundation -i "2" out.mpg
ffmpeg -f avfoundation -video_device_index 2 -i "default" out.mpg
# ffmpeg -f avfoundation -i "<screen device index>:<audio device index>" out.mov
# 在 OS X 中可查看屏幕尺寸 system_profiler SPDisplaysDataType |grep Resolution
# 使用空白的音频,修改像素格式
ffmpeg -f avfoundation -pixel_format bgr0 -s 640x480 -r 30 -i "default:none" out.avi
# 无损捕捉
# -qp 0 使用 x264 无损模式
# -preset ultrafast 使用快速模式
ffmpeg -video_size 1920x1080 -framerate 30 -f avfoundation -video_device_index 1 -i "default" -c:v libx264 -qp 0 -preset ultrafast capture.mkv
# 上述快速无损捕捉后,可对其进行慢速的无损压缩,减少视频文件尺寸
ffmpeg -i capture.mkv -c:v libx264 -qp 0 -preset veryslow capture_smaller.mkv
# 同时也录制麦克风的声音
ffmpeg -video_size 1280x720 -framerate 30 -f avfoundation -i "0:0" -c:v libx264 -qp 0 -preset ultrafast -c:a aac capture.mkv

VP9 Live#

http://wiki.webmproject.org/adaptive-streaming/instructions-to-do-webm-live-streaming-via-dash

# 创建直播内容
VP9_LIVE_PARAMS="-speed 6 -tile-columns 4 -frame-parallel 1 -threads 8 -static-thresh 0 -max-intra-rate 300 -deadline realtime -lag-in-frames 0 -error-resilient 1"
# Linux
ffmpeg \
-f v4l2 -input_format mjpeg -r 30 -s 1280x720 -i /dev/video0 \
-f alsa -ar 44100 -ac 2 -i hw:2 \
-map 0:0 \
-pix_fmt yuv420p \
-c:v libvpx-vp9 \
-s 1280x720 -keyint_min 60 -g 60 ${VP9_LIVE_PARAMS} \
-b:v 3000k \
-f webm_chunk \
-header "./glass_360.hdr" \
-chunk_start_index 1 \
./glass_360_%d.chk \
-map 1:0 \
-c:a libvorbis \
-b:a 128k -ar 44100 \
-f webm_chunk \
-audio_chunk_duration 2000 \
-header ./glass_171.hdr \
-chunk_start_index 1 \
./glass_171_%d.chk
# OS X
ffmpeg \
-r 30 -s 1280x720 -ar 44100 -ac 2 -f avfoundation -i "2:0" -c:v mjpeg \
-map 0:0 \
-pix_fmt yuv420p \
-c:v libvpx-vp9 \
-s 1280x720 -keyint_min 60 -g 60 ${VP9_LIVE_PARAMS} \
-b:v 3000k \
-f webm_chunk \
-header "./glass_360.hdr" \
-chunk_start_index 1 \
./glass_360_%d.chk \
-map 1:0 \
-c:a libvorbis \
-b:a 128k -ar 44100 \
-f webm_chunk \
-audio_chunk_duration 2000 \
-header ./glass_171.hdr \
-chunk_start_index 1 \
./glass_171_%d.chk
# 创建 DASH
ffmpeg \
-f webm_dash_manifest -live 1 \
-i ./glass_360.hdr \
-f webm_dash_manifest -live 1 \
-i ./glass_171.hdr \
-c copy \
-map 0 -map 1 \
-f webm_dash_manifest -live 1 \
-adaptation_sets "id=0,streams=0 id=1,streams=1" \
-chunk_start_index 1 \
-chunk_duration_ms 2000 \
-time_shift_buffer_depth 7200 \
-minimum_update_period 7200 \
./glass_live_manifest.mpd

RTSP#

ffmpeg -i space.mp4 -vcodec libx264 -tune zerolatency -crf 18 http://localhost:1234/feed1.ff

ffserver.conf

HTTPPort 1234
RTSPPort 1235
<Feed feed1.ffm>
File /tmp/feed1.ffm
FileMaxSize 2M
ACL allow 127.0.0.1
</Feed>
<Stream test1.sdp>
Feed feed1.ffm
Format rtp
Noaudio
VideoCodec libx264
AVOptionVideo flags +global_header
AVOptionVideo me_range 16
AVOptionVideo qdiff 4
AVOptionVideo qmin 10
AVOptionVideo qmax 51
ACL allow 192.168.0.0 192.168.255.255
</Stream>
mpv rtsp://192.168.0.xxx:1235/test1.sdp

ff* 通用选项#

-L Show license.
-h, -?, -help, --help [long|full] [decoder|encoder|demuxer|muxer|filter]=name
long 显示高级选项
full 显示完整的选项列表包括公共的和私有的
-version Show version.
-formats,-devices,-codecs,-protocols,-filters,-pix_fmts,-sample_fmts,-layouts,-colors,-decoders,-encoders,-bsfs
显示所有支持的格式,设备,编码,协议,过滤器,香色格式,颜色名字等...
bsfs Show available bitstream filters.
codes 更明确地说是 media bitstream format

视频尺寸和缩写#

缩写尺寸
ntsc720x480
pal720x576
qntsc352x240
qpal352x288
sntsc640x480
spal768x576
film352x240
ntsc-film352x240
sqcif128x96
qcif176x144
cif352x288
4cif704x576
16cif1408x1152
qqvga160x120
qvga320x240
vga640x480
svga800x600
xga1024x768
uxga1600x1200
qxga2048x1536
sxga1280x1024
qsxga2560x2048
hsxga5120x4096
wvga852x480
wxga1366x768
wsxga1600x1024
wuxga1920x1200
woxga2560x1600
wqsxga3200x2048
wquxga3840x2400
whsxga6400x4096
whuxga7680x4800
cga320x200
ega640x350
hd480852x480
hd7201280x720
hd10801920x1080
2k2048x1080
2kflat1998x1080
2kscope2048x858
4k4096x2160
4kflat3996x2160
4kscope4096x1716
nhd640x360
hqvga240x160
wqvga400x240
fwqvga432x240
hvga480x320
qhd960x540
2kdci2048x1080
4kdci4096x2160
uhd21603840x2160
uhd43207680x4320

视频速率和缩写#

缩写速率
ntsc30000/1001
pal25/1
qntsc30000/1001
qpal25/1
sntsc30000/1001
spal25/1
film24/1
ntsc-film24000/1001

ffserver#

# 启动流媒服务器
ffserver -f ffserver.conf

farm#

https://www.ffmpeg.org/ffmpeg-devices.html http://www.squidnetsoftware.com/

https://trac.ffmpeg.org/wiki/Encode/PremierePro https://video.stackexchange.com/a/15799

# Server
ffmpeg -i tcp://[your server IP]:[The same port you entered in step 2]?listen -c:v libx264 -preset medium -crf 23 -pix_fmt yuv420p -c:a libfdk_aac -vbr 4 output2.mp4
# Client
ffmpeg -i frameserver.avs -f mpegts tcp://[IP address of your server]:[open port on your server]

FAQ#

video:23799kB audio:1406kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown#

Invalid frame dimensions 0x0#

出现这样的错误时,不必关心,一会儿过后就能正常播放了.

tbr tbn tbc#

FFMpeg 会使用三种不同的时间戳来做不同的工作.

  • tbr
    • tbr is guessed from the video stream and is the value users want to see when they look for the video frame rate
    • 代表帧率,和 demuxer 相关
  • tbn
    • the time base in AVStream that has come from the container
    • 代表文件层(st)的时间精度,即 1S=1200k,和 duration 相关;
  • tbc
    • the time base in AVCodecContext for the codec used for a particular stream
    • tbc 代表视频层(st->codec)的时间精度,即 1S=50,和 strem->duration 和时间戳相关。

例如: 25 tbr 90k tbn 50 tbc

当这几个值无法检测到时,其值可能为 1000k tbr, 1000k tbn, 1000k tbc

Reference#

https://trac.ffmpeg.org/wiki/EncodingForStreamingSites https://trac.ffmpeg.org/wiki/Encode/AAC