How to use FFMPEG
FFmpeg is a command line tool that is composed of a collection of free software / open source libraries. It includes libavcodec, an audio/video codec library used by several other projects, and libavformat, an audio/video container mux and demux library. Useful ffmpeg Commands are given below. These are taken from man pages of ffmpeg. But I think this will help some one who is not familiar with linux.
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* To set the video bitrate of the output file to 64kbit/s:
{codecitation}ffmpeg -i input.avi -b 64k output.avi{/codecitation}
* To force the frame rate of the output file to 24 fps:
{codecitation}ffmpeg -i input.avi -r 24 output.avi{/codecitation}
* To force the frame rate of the input file (valid for raw formats only) to 1 fps and the frame rate of the output file to 24 fps:
{codecitation}ffmpeg -r 1 -i input.m2v -r 24 output.avi{/codecitation}
* FFmpeg can grab video and audio from devices given that you specify the input format and device.
{codecitation}ffmpeg -f oss -i /dev/dsp -f video4linux2 -i /dev/video0 /tmp/out.mpg{/codecitation}
* FFmpeg can grab the X11 display from TV viewer
{codecitation}ffmpeg -f x11grab -s cif -i :0.0 /tmp/out.mpg{/codecitation}
* Set several input files and output files:
{codecitation}ffmpeg -i /tmp/a.wav -s 640x480 -i /tmp/a.yuv /tmp/a.mpg{/codecitation}
* Converts a.wav to MPEG audio at 22050 Hz sample rate.
{codecitation}ffmpeg -i /tmp/a.wav -ar 22050 /tmp/a.mp2{/codecitation}
* Encode to several formats at the same time and define a mapping from input stream to output streams:
{codecitation}ffmpeg -i /tmp/a.wav -ab 64k /tmp/a.mp2 -ab 128k /tmp/b.mp2 -map 0:0 -map 0:0{/codecitation}
* Extract images from a video, or create a video from many images:
{codecitation}ffmpeg -i foo.avi -r 1 -s WxH -f image2 foo-%03d.jpeg{/codecitation}
{codecitation}ffmpeg -f image2 -i foo-%03d.jpeg -r 12 -s WxH foo.avi{/codecitation}
These are some of the oprions you can use.
OPTIONS
Main options
-L Show license.
-h Show help.
-version
Show version.
-formats
Show available formats, codecs, bitstream filters, protocols, and frame size and frame rate abbreviations.
The fields preceding the format and codec names have the following meanings:
D Decoding available
E Encoding available
V/A/S
Video/audio/subtitle codec
S Codec supports slices
D Codec supports direct rendering
T Codec can handle input truncated at random locations instead of only at frame boundaries
-f fmt
Force format.
-i filename
input file name
-y Overwrite output files.
-t duration
Restrict the transcoded/captured video sequence to the duration specified in seconds. "hh:mm:ss[.xxx]" syntax is also supported.
-fs limit_size
Set the file size limit.
-ss position
Seek to given time position in seconds. "hh:mm:ss[.xxx]" syntax is also supported.
-itsoffset offset
Set the input time offset in seconds. "[-]hh:mm:ss[.xxx]" syntax is also supported. This option affects all the input files that follow it. The offset is added
to the timestamps of the input files. Specifying a positive offset means that the corresponding streams are delayed by ’offset’ seconds.
-timestamp time
Set the timestamp.
-metadata key=value
Set a metadata key/value pair.
ffmpeg -i in.avi -metadata title="my title"
-v number
Set the logging verbosity level.
-target type
Specify target file type ("vcd", "svcd", "dvd", "dv", "dv50", "pal-vcd", "ntsc-svcd", ... ). All the format options (bitrate, codecs, buffer sizes) are then set
automatically. You can just type:
ffmpeg -i myfile.avi -target vcd /tmp/vcd.mpg
Nevertheless you can specify additional options as long as you know they do not conflict with the standard, as in:
ffmpeg -i myfile.avi -target vcd -bf 2 /tmp/vcd.mpg
-dframes number
Set the number of data frames to record.
-scodec codec
Force subtitle codec (’copy’ to copy stream).
-newsubtitle
Add a new subtitle stream to the current output stream.
-slang code
Set the ISO 639 language code (3 letters) of the current subtitle stream.
Video Options
-b bitrate
Set the video bitrate in bit/s (default = 200 kb/s).
-vframes number
Set the number of video frames to record.
-r fps
Set frame rate (Hz value, fraction or abbreviation), (default = 25).
-s size
Set frame size. The format is wxh (ffserver default = 160x128, ffmpeg default = same as source). The following abbreviations are recognized:
sqcif
128x96
qcif
176x144
cif 352x288
4cif
704x576
16cif
1408x1152
qqvga
160x120
qvga
320x240
vga 640x480
svga
800x600
xga 1024x768
uxga
1600x1200
qxga
2048x1536
sxga
1280x1024
qsxga
2560x2048
hsxga
5120x4096
wvga
852x480
wxga
1366x768
wsxga
1600x1024
wuxga
1920x1200
woxga
2560x1600
wqsxga
3200x2048
wquxga
3840x2400
whsxga
6400x4096
whuxga
7680x4800
cga 320x200
ega 640x350
hd480
852x480
hd720
1280x720
hd1080
1920x1080
-aspect aspect
Set aspect ratio (4:3, 16:9 or 1.3333, 1.7777).
-croptop size
Set top crop band size (in pixels).
-cropbottom size
Set bottom crop band size (in pixels).
-cropleft size
Set left crop band size (in pixels).
-cropright size
Set right crop band size (in pixels).
-padtop size
Set top pad band size (in pixels)
Use same video quality as source (implies VBR).
-pass n
Select the pass number (1 or 2). It is used to do two-pass video encoding. The statistics of the video are recorded in the first pass into a log file (see also the
option -passlogfile), and in the second pass that log file is used to generate the video at the exact requested bitrate. On pass 1, you may just deactivate audio
and set output to null, examples for Windows and Unix:
ffmpeg -i foo.mov -vcodec libxvid -pass 1 -an -f rawvideo -y NUL
ffmpeg -i foo.mov -vcodec libxvid -pass 1 -an -f rawvideo -y /dev/null
-passlogfile prefix
Set two-pass log file name prefix to prefix, the default file name prefix is ‘‘ffmpeg2pass’’. The complete file name will be PREFIX-N.log, where N is a number
specific to the output stream.
-newvideo
Add a new video stream to the current output stream.
Advanced Video Options
-pix_fmt format
Set pixel format. Use ’list’ as parameter to show all the supported pixel formats.
-sws_flags flags
Set SwScaler flags (only available when compiled with swscale support).
-g gop_size
Set the group of pictures size.
-intra
Use only intra frames.
-vdt n
Discard threshold.
-qscale q
Use fixed video quantizer scale (VBR).
-qmin q
minimum video quantizer scale (VBR)
-qmax q
maximum video quantizer scale (VBR)
-qdiff q
maximum difference between the quantizer scales (VBR)
-qblur blur
video quantizer scale blur (VBR) (range 0.0 - 1.0)
-qcomp compression
video quantizer scale compression (VBR) (default 0.5). Constant of ratecontrol equation. Recommended range for default rc_eq: 0.0-1.0
-lmin lambda
minimum video lagrange factor (VBR)
-lmax lambda
max video lagrange factor (VBR)
-mblmin lambda
minimum macroblock quantizer scale (VBR)
-mblmax lambda
maximum macroblock quantizer scale (VBR)
These four options (lmin, lmax, mblmin, mblmax) use ’lambda’ units, but you may use the QP2LAMBDA constant to easily convert from ’q’ units:
ffmpeg -i src.ext -lmax 21*QP2LAMBDA dst.ext
-rc_init_cplx complexity
initial complexity for single pass encoding
-b_qfactor factor
qp factor between P- and B-frames
-i_qfactor factor
qp factor between P- and I-frames
-b_qoffset offset
qp offset between P- and B-frames
-i_qoffset offset
qp offset between P- and I-frames
-rc_eq equation
Set rate control equation (default = "tex^qComp").
-rc_override override
rate control override for specific intervals
-me_method method
Set motion estimation method to method. Available methods are (from lowest to best quality):
zero
Try just the (0, 0) vector.
phods
log
x1
hex
umh
epzs
(default method)
full
exhaustive search (slow and marginally better than epzs)
-dct_algo algo
Set DCT algorithm to algo. Available values are:
0 FF_DCT_AUTO (default)
1 FF_DCT_FASTINT
2 FF_DCT_INT
3 FF_DCT_MMX
4 FF_DCT_MLIB
5 FF_DCT_ALTIVEC
-idct_algo algo
Set IDCT algorithm to algo. Available values are:
0 FF_IDCT_AUTO (default)
1 FF_IDCT_INT
2 FF_IDCT_SIMPLE
3 FF_IDCT_SIMPLEMMX
4 FF_IDCT_LIBMPEG2MMX
5 FF_IDCT_PS2
6 FF_IDCT_MLIB
7 FF_IDCT_ARM
8 FF_IDCT_ALTIVEC
9 FF_IDCT_SH4
10 FF_IDCT_SIMPLEARM
-er n
Set error resilience to n.
1 FF_ER_CAREFUL (default)
2 FF_ER_COMPLIANT
3 FF_ER_AGGRESSIVE
4 FF_ER_VERY_AGGRESSIVE
-ec bit_mask
Set error concealment to bit_mask. bit_mask is a bit mask of the following values:
1 FF_EC_GUESS_MVS (default = enabled)
2 FF_EC_DEBLOCK (default = enabled)
-bf frames
Use ’frames’ B-frames (supported for MPEG-1, MPEG-2 and MPEG-4).
-mbd mode
macroblock decision
0 FF_MB_DECISION_SIMPLE: Use mb_cmp (cannot change it yet in FFmpeg).
1 FF_MB_DECISION_BITS: Choose the one which needs the fewest bits.
2 FF_MB_DECISION_RD: rate distortion
-4mv
Use four motion vector by macroblock (MPEG-4 only).
-part
Use data partitioning (MPEG-4 only).
-bug param
Work around encoder bugs that are not auto-detected.
-strict strictness
How strictly to follow the standards.
-aic
Enable Advanced intra coding (h263+).
-umv
Enable Unlimited Motion Vector (h263+)
-deinterlace
Deinterlace pictures.
-ilme
Force interlacing support in encoder (MPEG-2 and MPEG-4 only). Use this option if your input file is interlaced and you want to keep the interlaced format for
minimum losses. The alternative is to deinterlace the input stream with -deinterlace, but deinterlacing introduces losses.
-psnr
Calculate PSNR of compressed frames.
-vstats
Dump video coding statistics to vstats_HHMMSS.log.
-vstats_file file
Dump video coding statistics to file.
-top n
top=1/bottom=0/auto=-1 field first
-dc precision
Intra_dc_precision.
-vtag fourcc/tag
Force video tag/fourcc.
-qphist
Show QP histogram.
-vbsf bitstream_filter
Bitstream filters available are "dump_extra", "remove_extra", "noise", "h264_mp4toannexb", "imxdump", "mjpegadump".
ffmpeg -i h264.mp4 -vcodec copy -vbsf h264_mp4toannexb -an out.h264
Audio Options
-aframes number
Set the number of audio frames to record.
-ar freq
Set the audio sampling frequency (default = 44100 Hz).
-ab bitrate
Set the audio bitrate in bit/s (default = 64k).
-ac channels
Set the number of audio channels (default = 1).
-an Disable audio recording.
-acodec codec
Force audio codec to codec. Use the "copy" special value to specify that the raw codec data must be copied as is.
-newaudio
Add a new audio track to the output file. If you want to specify parameters, do so before "-newaudio" ("-acodec", "-ab", etc..).
Mapping will be done automatically, if the number of output streams is equal to the number of input streams, else it will pick the first one that matches. You can
override the mapping using "-map" as usual.
Example:
ffmpeg -i file.mpg -vcodec copy -acodec ac3 -ab 384k test.mpg -acodec mp2 -ab 192k -newaudio
-alang code
Set the ISO 639 language code (3 letters) of the current audio stream.
Advanced Audio options:
-atag fourcc/tag
Force audio tag/fourcc.
-absf bitstream_filter
Bitstream filters available are "dump_extra", "remove_extra", "noise", "mp3comp", "mp3decomp".
Subtitle options:
-scodec codec
Force subtitle codec (’copy’ to copy stream).
-newsubtitle
Add a new subtitle stream to the current output stream.
-slang code
Set the ISO 639 language code (3 letters) of the current subtitle stream.
-sbsf bitstream_filter
Bitstream filters available are "mov2textsub", "text2movsub".
ffmpeg -i file.mov -an -vn -sbsf mov2textsub -scodec copy -f rawvideo sub.txt
Audio/Video grab options
-vc channel
Set video grab channel (DV1394 only).
-tvstd standard
Set television standard (NTSC, PAL (SECAM)).
-isync
Synchronize read on input.
Advanced options
-map input_stream_id[:sync_stream_id]
Set stream mapping from input streams to output streams. Just enumerate the input streams in the order you want them in the output. sync_stream_id if specified
sets the input stream to sync against.
-map_meta_data outfile:infile
Set meta data information of outfile from infile.
-debug
Print specific debug info.
-benchmark
Add timings for benchmarking.
-dump
Dump each input packet.
-hex
When dumping packets, also dump the payload.
-bitexact
Only use bit exact algorithms (for codec testing).
-ps size
Set RTP payload size in bytes.
-re Read input at native frame rate. Mainly used to simulate a grab device.
-loop_input
Loop over the input stream. Currently it works only for image streams. This option is used for automatic FFserver testing.
-loop_output number_of_times
Repeatedly loop output for formats that support looping such as animated GIF (0 will loop the output infinitely).
-threads count
Thread count.
-vsync parameter
Video sync method. Video will be stretched/squeezed to match the timestamps, it is done by duplicating and dropping frames. With -map you can select from which
stream the timestamps should be taken. You can leave either video or audio unchanged and sync the remaining stream(s) to the unchanged one.
-async samples_per_second
Audio sync method. "Stretches/squeezes" the audio stream to match the timestamps, the parameter is the maximum samples per second by which the audio is changed.
-async 1 is a special case where only the start of the audio stream is corrected without any later correction.
-copyts
Copy timestamps from input to output.
-shortest
Finish encoding when the shortest input stream ends.
-dts_delta_threshold
Timestamp discontinuity delta threshold.
-muxdelay seconds
Set the maximum demux-decode delay.
-muxpreload seconds
Set the initial demux-decode delay.
Preset files
A preset file contains a sequence of option=value pairs, one for each line, specifying a sequence of options which would be awkward to specify on the command line.
Lines starting with the hash (’#’) character are ignored and are used to provide comments. Check the ffpresets directory in the FFmpeg source tree for examples.
Preset files are specified with the "vpre", "apre" and "spre" options. The options specified in a preset file are applied to the currently selected codec of the same
type as the preset option.
The argument passed to the preset options identifies the preset file to use according to the following rules.
First ffmpeg searches for a file named arg.ffpreset in the directories $HOME/.ffmpeg, and in the datadir defined at configuration time (usually PREFIX/share/ffmpeg) in
that order. For example, if the argument is "libx264-max", it will search for the file libx264-max.ffpreset.
If no such file is found, then ffmpeg will search for a file named codec_name-arg.ffpreset in the above-mentioned directories, where codec_name is the name of the codec
to which the preset file options will be applied. For example, if you select the video codec with "-vcodec libx264" and use "-vpre max", then it will search for the
file libx264-max.ffpreset.
Finally, if the above rules failed and the argument specifies an absolute pathname, ffmpeg will search for that filename. This way you can specify the absolute and
complete filename of the preset file, for example ./ffpresets/libx264-max.ffpreset.
FFmpeg formula evaluator
When evaluating a rate control string, FFmpeg uses an internal formula evaluator.
The following binary operators are available: "+", "-", "*", "/", "^".
The following unary operators are available: "+", "-", "(...)".
The following statements are available: "ld", "st", "while".
The following functions are available:
sinh(x)
cosh(x)
tanh(x)
sin(x)
cos(x)
tan(x)
atan(x)
asin(x)
acos(x)
exp(x)
log(x)
abs(x)
squish(x)
gauss(x)
mod(x, y)
max(x, y)
min(x, y)
eq(x, y)
gte(x, y)
gt(x, y)
lte(x, y)
lt(x, y)
bits2qp(bits)
qp2bits(qp)
The following constants are available:
PI
E
iTex
pTex
tex
mv
fCode
iCount
mcVar
var
isI
isP
isB
avgQP
qComp
avgIITex
avgPITex
avgPPTex
avgBPTex
avgTex
