Filters One-Liners

Foreword

This page contains one-liners illustrating the many possibilities of GPAC filters architecture. For a more detailed information, it is highly recommended that you read:

• the general concepts page
• the gpac application help

To get a better understanding of each command illustrated in this case, it is recommended to:

• run the same command with -graph specified to see the filter graph associated
• read the help of the different filters in this graph using gpac -h filter_name

Whenever an option is specified, e.g. dest.mp4:foo, you can get more info and locate the parent filter of this option using gpac -h foo.

The filter session is by default quiet, except for warnings and error reporting. To get information on the session while running, use -r option. To get more runtime information, use the log system.

Given the configurable nature of the filter architecture, most examples given in one context can be reused in another context. For example:

• from the dump examples:
  

  gpac -i source reframer:saps=1 -o dump/$num$.png
  

• from the encode examples:
  

  gpac -i source ffsws:osize=320x240 enc:c=avc:b=1m -o dst.mp4
  

This can be recombine as dump key frames to png while rescaling:

gpac -i source reframer:saps=1 ffsws:osize=128x72 -o dump/$num$.png

NOTE The command lines given here are usually using a local file for source or destination URLs, but they can work with remote URLs as well.

Reminder
Most filters are never specified at the prompt, they are dynamically loaded during the graph resolution.
GPAC filters can use either:

• global options, e.g. --foo, applying to each instance of any filter defining the foo option,
• local options to a given filter and any filters dynamically loaded, e.g. :foo. This is called argument inheriting.

NOTE This page is under permanent construction, feel free to contribute !

Source Inspection

Check if a source is supported and get quick information on the media streams - see filter, howto

gpac -i source inspect
gpac -info source

Check if a source is supported and get verbose information on the media streams - see filter, howto

gpac -i source inspect:full

Check if a source is supported and get all possible media stream states in the media streams (codec change & co) - see filter, howto

gpac -i source inspect:allp

Dump all packets info of a source from 60 to 80 seconds, listing one stream after the other - see filter

gpac -i source inspect:deep:start=60:dur=20:interleave=false

Dump CTS, DTS, random access and size of packets of a source to a log file - see filter, howto

gpac -i source inspect:deep:fmt="%dts% %dts% %sap% %size%%lf":log=mylogs.txt

Analyze packets of a source - see filter, howto

gpac -i source.264 inspect:deep:analyze=on

Note This is similar to (but more complete than) MP4Box -dnal option

Count all streams in a source - see filter, doc
`` res =gpac -i source probe`

Count all AC3 audio streams in a source - _see [filter](../Filters/probe.md),  [doc](../Filters/filters_general.md#filters_general)_  
 ```
res = `gpac -i source @#CodecID=ac3 probe`

Dumping and decoding

Extract AVC track, potentially transcoding - see filter

gpac -i source -o dst.264

Extract AVC track if any - see filter

gpac -i source @#CodecID=avc -o dst.264

Extract AAC track - see filter

gpac -i source -o dst.aac

Decode audio track to 16 bit pcm - see filter

gpac -i source -o dst.wav

Decode video track to YUV 420 - see filter

gpac -i source -o dst_$Width_$Height$.yuv

Decode video track starting from frame 2s for 1s to YUV 420 - see filter

gpac -i source -o dst_$Width_$Height$.yuv:start=2:dur=1

Dump video track key frames to PNG see filter

gpac -i source reframer:saps=1 -o dump/$num$.png

Extract all tracks - see filter

gpac -i source reframer -o dump_$ID$:dynext

Extract all audio tracks - see doc

gpac -i source reframer @#audio -o dump_$ID$:dynext

Extract all AAC audio tracks - see doc

gpac -i source reframer @#CodecID=aac -o dump_$ID$:dynext

Multiplexing

Mux sources to MP4 - see filter

gpac -i source -i source2 -o dst.mp4

Mux sources to MP4 specifying language - see doc

gpac -i source -i source2:#Language=fr -o dst.mp4

Mux sources to fMP4 - see filter

gpac -i source -i source2 -o dst.mp4:frag

Force remultiplexing an MP4 (all syntaxes are equivalent) - see filter

gpac -i source.mp4 reframer -o dst.mp4
gpac -i source.mp4 -o dst.mp4:remux
gpac -i source.mp4 -o dst.mp4:store=inter
gpac -i source.mp4 -o dst.mp4:inter

Mux sources to single program MPEG-2 TS - see filter

gpac -i source -i source2 -o dst.ts

Mux sources to MPEG-2 TS, specifying service ID - see filter

gpac -i source:#ServiceID=1 -i source2:#ServiceID=2 -o dst.ts

Mux sources to MPEG-2 TS with a target mux rate - see filter

gpac -i source:#ServiceID=1 -i source2:#ServiceID=2 -o dst.ts:rate=10m

Mux sources to MKV (for builds with FFmpeg support) - see filter

gpac -i source -o dst.mkv

Remultiplexing

Remux sources to MP4 forcing bitstream reparsing (all syntaxes are equivalent)

gpac -i source unframer -o dst.mp4
MP4Box -add source:unframer -new dst.mp4

Encoding

Encode an MP3 to an AAC file at 100 kbps - see filter

gpac -i source.mp3 -o dst.aac:b=100k

Encode an MP3 to AAC in MP4 file at 100 kbps - see filter

gpac -i source.mp3 enc:c=aac:b=100k -o dst.mp4

Transcode to AAC at 100 kbps and AVC at 1m, intra every 2s - see filter

gpac -i source enc:c=aac:b=100k:FID=1 enc:c=avc:b=1m:fintra=2:FID=2 -o dst.mp4:SID=1,2

Rescale video and encode to AVC at 1m, leaving other streams if any unmodified - see filter

gpac -i source ffsws:osize=320x240 enc:c=avc:b=1m -o dst.mp4

Rescale YUV video and encode to AVC at 1m - see filter

gpac -i source.yuv:size=1280x720 ffsws:osize=320x240 enc:c=avc:b=1m -o dst.mp4

Resample audio to 48khz - see filter

gpac -i source resample:sr=48k -o dump.pcm
gpac -i source.pcm:sr=44100:ch=1 resample:sr=48k -o dump.pcm

Setting FFmpeg and x264 options - see filter

gpac -i vid.mp4 enc:c=avc:b=2m:fintra=2:vprofile=baseline:preset=ultrafast:tune=zerolatency::x264-params=no-mbtree:sliced-threads:sync-lookahead=0 -o dst.mp4

Transcode to AVC 1mbps and aac 128k while monitoring video output and filter stats- see filter

gpac -i source enc:c=avc:b=1m enc:c=aac:b=128k -o dst.mp4 vout:vsync=0 -r

Downscale and transcode to AVC 1mbps and aac 128k while monitoring video output - see filter

gpac -i source ffsws:osize=256x144 enc:c=avc:b=1m enc:c=aac:b=128k -o dst.mp4 vout:vsync=0

Use two-pass encoding with FFmpeg (libx264 only for GPAC 2.0, all codecs for higher versions) - see filter

##first pass
gpac -i source enc:c=avc:b=3m:pass1 -o null
##second pass
gpac -i source enc:c=avc:b=3m:pass2 -o dst.mp4

Rescaling

rescale without respecting aspect ratio

gpac -i source1.mp4 ffsws:osize=512x512 vout

rescale respecting aspect ratio and pad color to red

gpac -i source1.mp4 ffsws:osize=512x512:keepar=full:padclr=red vout

rescale without respecting aspect ratio nut set output aspect ratio, output video will be 340x512 (340=510*2/3 )

gpac -i source1.mp4 ffsws:osize=510x512:osr=3/2 vout

Encryption

Encrypt and dash several sources using a single drm configuration - see filter

gpac -i source1.mp4 -i source2.aac cecrypt:cfile=drm.xml -o live.mpd

Encrypt and dash several sources using one drm configuration per source - see filter

gpac -i source1.mp4:#CryptInfo=drm1.xml -i source2.aac:#CryptInfo=drm1.xml cecrypt -o live.mpd

perform pre-dashing before encryption for key roll at segment boundaries - see filter

gpac -i source.mp4 dasher:gencues cecrypt:cfile=roll_seg.xml -o live.mpd

Piping and sockets

Grab a compressed stream (e.g. AVC|H264) from stdin, remove all non I-frames and non-video PIDs and output as raw 264 over stdout - see filter howto

gpac -i - @#video reframer:saps=1 -o stdout:ext=264

Grab a raw stream (e.g. YUV420) from stdin and output as raw 264 over stdout - see filter howto

gpac -i stdin:ext=yuv:size=1280x720 -o stdout:ext=264

Grab a TS UDP stream and remux as fragmented mp4 over a named pipe - see filter howto

gpac -i udp://234.0.0.1:1234 -o pipe://mypipe:ext=mp4:mkp:frag

Mux source to real-time M2TS UDP multicast stream - see filter howto

gpac -i source.mp4 -o udp://234.0.0.1:1234/:ext=ts:realtime

DASH and HLS generation

See Howtos DASH, DASH Low Latency and dasher filter.

Generating a live profile, static MPD

gpac -i source.mp4 -i source2.mp4  -o dash/live.mpd

Generating a onDemand profile, static MPD from a source

gpac -i source.mp4 -i source2.mp4 -o dash/live.mpd:profile=onDemand

Generating a HLS with one file per segment

gpac -i source.mp4 -i source2.mp4 -o dash/live.m3u8

Generating a HLS with single file from a source

gpac -i source.mp4 -i source2.mp4 -o dash/live.m3u8:sfile

Generating a HLS and MPD with one file per segment

gpac -i source.mp4 -i source2.mp4 -o dash/live.mpd:dual

Generating a HLS with single file and MPD from a source

gpac -i source.mp4 -i source2.mp4 -o dash/live.mpd:dual:profile=onDemand

Generating a live profile, dynamic offering

gpac -i source.mp4 -i source2.mp4 -o dash/live.mpd:dmode=dynamic

Generating a live profile, dynamic offering with time regulation at each segment

gpac -i source.mp4 -i source2.mp4 -o dash/live.mpd:dmode=dynamic:sreg

Generating a live profile, low-latency, dynamic offering with time regulation at each frame

gpac -i source.mp4 -i source2.mp4 reframer:rt=on -o dash/live.mpd:dmode=dynamic:segdur=1:cdur=0.1

Generating a live profile, low-latency, dynamic offering with time regulation at each frame and offering it as HTTP, with 1h timeshift

gpac -i source.mp4 -i source2.mp4 reframer:rt=on -o http://127.0.0.1:8080/live.mpd:gpac:dmode=dynamic:segdur=1:cdur=0.1:rdirs=/tmp:tsb=3600

Looping two sources to simulate a live over http

gpac --floop=-1 flist:srcs=source.mp4 flist:srcs=source2.mp4 reframer:rt=on -o http://127.0.0.1:8080/live.mpd:gpac:dmode=dynamic:segdur=1:cdur=0.1:rdirs=/tmp:tsb=3600

Live UTC counter single resolution over HTTP in low latency

gpac avgen enc:c=aac:b=100k:FID=1 enc:c=avc:b=2m:fintra=1:FID=2 -o http://127.0.0.1:8080/live.mpd:gpac:SID=1,2:dmode=dynamic:segdur=1:cdur=0.1:rdirs=/tmp

Live UTC counter 2 resolutions over HTTP in low latency

gpac avgen:sizes=1280x720,1920x1080:rates=2M,5M enc:c=aac:b=100k:FID=1 enc:c=avc:fintra=1:FID=2 -o http://127.0.0.1:8080/live.mpd:gpac:SID=1,2:dmode=dynamic:segdur=1:cdur=0.1:rdirs=/tmp

Generate trick mode from source1 and use both source1 A+V, source2 V and trick mode in dash:

gpac -i source1.mp4 @#video reframer:saps=1 -i source2.mp4 @#video @1 @@ -o dash/live.mpd

Insert custom DASH tags in manifest:

gpac -i source:#RDesc=<rep_desc>bar</rep_desc>:#ASCDesc=<as_desc>bar</as_desc>:#PDesc=<p_desc>bar</p_desc> -o manifest.mpd

Insert custom HLS tags in manifest (global tags use hlsx option and per-PID tags use HLSMExt property) and variant playlists (HLSVExt PID property):

gpac -i source::#HLSMExt=vfoo,vbar=video::#HLSVExt=#fooVideo,#bar1=optVideo -i source2::#HLSMExt=afoo,abar=audio-en::#HLSVExt=#fooAudio,#bar1=optAudio -o manifest.m3u8::hlsx=#SomeExt,#SomeOtherExt=true

Time modification

Note: If the source is an MP4 file, it is much simpler/faster to perform these operations using MP4Box

Add 200 ms delay to audio (audio later than other streams) - see filter

gpac -i source restamp:delay_a=2/10 -o dst

Add -1s delay to audio (audio earlier than other streams) - see filter

gpac -i source restamp:delay_a=-1 -o dst

Speedup all tracks except audio by 10% (speed 1.1) - see filter

gpac -i source restamp:fps=-11/10 -o dst

Change video FPS to 29.97 with frame cloning - see filter

gpac -i source restamp:fps=30000/1001:rawv=force -o dst

Source splitting

Extract from 1min to 2min30s - see filter

gpac -i source reframer:xs=T00:01:00:xe=T00:02:30 -o dst

Extract from 1min to 2min30s after decoding (sample-accurate audio) - see filter

gpac -i source reframer:raw=av::xs=T00:01:00:xe=T00:02:30 -o dst

Extract from 1min to 2min30s and 5min20s to 6min - see filter

gpac -i source reframer:xs=T00:01:00,T00:05:20:xe=T00:02:30,T00:06:00 -o dst

Extract from 5min20s to end - see filter

gpac -i source reframer:xs=T00:05:20 -o dst

Extract from 1min to 2min30s and 5min20s to end - see filter

gpac -i source reframer:xs=T00:01:00,T00:05:20:xe=T00:02:30 -o dst

Playlists and source concatenation

Loop file forever playback - see filter

gpac flist:srcs=source.mp4:floop=-1 aout vout

Read all PNGs from a directory, sorting by creation date - see filter

gpac flist:srcs=src/*.png:fsort=date vout

Resize a set of videos with aspect ratio respected - see filter

gpac flist:srcs=1.mp4,2.mp4,3.mp4 ffsws:osize=1280x720:keepar=full c=avc -o dst.mp4

Concatenate all MP4 from directory dir:

gpac flist:srcs=*.mp4 vout

##same as above but through a playlist
ls *.mp4 > pl.m3u
gpac -i pl.m3u vout

Playback

Basic playback - see howto

gpac -play source

Video only playback - see howto

gpac -i source vout

Video only playback, no sync - see howto

gpac -i source vout:sync=0

Audio only playback - see howto

gpac -i source aout

Single-threaded GUI playback - see howto

gpac compositor:player=gui:src=source
gpac -threads=0 -gui source

Single-threaded compositor playback (available as alias -mp4c) - see howto

gpac compositor:player=base:src=source
gpac -threads=0 -mp4c source

NOTE The -mp4c and -gui aliases will by default set -threads=2.

Thumbnails

Create thumbnails based on key frames in source, with at least 30 seconds between frames and dynamic thumbnail height

gpac -i src reframer:saps=1 thumbs:snap=30 -o dump_$num$.png

Create thumbnails based on key frames in source, with at least 30 seconds between frames in a 6x6 layout with 5x downscale and json generation

gpac -i src reframer:saps=1 thumbs:snap=30:grid=6x6:list=thumbs.json:scale=5 -o dump_$num$.png

Create thumbnails of scene cuts based on key frames in source

gpac -i src reframer:saps=1 thumbs:snap=0:mae=15 -o dump_$num$.png

Use thumbnailer to overlay frame time over video

gpac -i src thumbs:grid=1x1:txt='$time$' vout

Filter Blacklist

Decode source disabling hardware decoders:

gpac -blacklist=vtbdec,nvdec source vout

Decode source MP4 enabling only the minimum filters:

gpac -blacklist=-fin,mp4dmx,ffdec,vout source.mp4 vout

FFmpeg support

Set gpac as RTMP output server

gpac -i src.mp4 -o rtmp://127.0.0.1:8888/live:gpac:ffmt=flv:rtmp_listen=1

Read from RTMP server

gpac -i rtmp://127.0.0.1:8888/live vout aout

Set gpac as RTMP input server, and use another instance to push

gpac -i rtmp://127.0.0.1:8888/live:gpac:rtmp_listen=1 vout aout
gpac -i src.mp4 -o rtmp://127.0.0.1:8888/live:gpac:ffmt=flv

Read audio and video from device

gpac -i av:// vout aout

Read video from device

gpac -i video:// vout

Read audio from device

gpac -i audio:// aout

read from screen on OSX

gpac -i video://:fmt=avfoundation:dev=screen0 vout

read from screen on Linux

gpac -i video://:fmt=x11grab:dev=:0.0 vout

Read audio after filter from libavfilter (compressor here)

gpac -i audio.mp4 ffavf:afmt=s16:sr=44100::f=acompressor aout

Read video after filter from libavfilter (negate here)

gpac -i video.mp4 ffavf::f=negate vout

Use audio to video filter from libavfilter (showspectrum here)

gpac -i audio.mp4 ffavf:pfmt=yuv::f=showspectrum=size=320x320 aout vout

Use 2 video to video filter from libavfilter (overlay here)

gpac -i video1.mp4:#ffid=a -i video2.mp4:#ffid=b ffavf:pfmt=yuv::f=[a][b]overlay=main_w-overlay_w-10:main_h-overlay_h-10 vout

Compute PSNR

gpac -i video.mp4:#ffid=dist -i ref.mp4:#ffid=ref ffavf::'f=[dist][ref]psnr=f=psnr.log' -o null

Compute SSIM

gpac -i video.mp4:#ffid=dist -i ref.mp4:#ffid=ref ffavf::'f=[dist][ref]ssim=f=ssim.log' -o null

Compute PSNR and SSIM

gpac -i video.mp4:#ffid=dist -i ref.mp4:#ffid=ref \
    @@ @@1 ffavf::'f=[dist][ref]psnr=f=psnr2.log' @ -o null \
    @@ @@1 ffavf::f='[dist][ref]ssim=f=ssim2.log' @ -o null

SRT session from local file (requires FFmpeg with SRT support)

##player listening for SRT handshake
gpac -play srt://127.0.0.1:1234:gpac:mode=listener
##streamer with real-time regulation
gpac -i video.mp4 reframer:rt=on -o srt://127.0.0.1:1234:gpac:ffmt=mpegts

SRT session from avgen filter (requires FFmpeg with SRT support)

##player listening for SRT handshake
gpac -play srt://127.0.0.1:1234:gpac:mode=listener
##streamer with real-time regulation
gpac avgen reframer:rt=on c=avc c=aac -o srt://127.0.0.1:1234:gpac:ffmt=mpegts

Graphics

All examples give the content of the JSON playlist (named mix.json here) - see filter, howto
The result can be viewed using gpac avmix:pl=mix.json vout (live mode) or gpac avmix:live=0:pl=mix.json vout (offline mode).

Insert text over video:

[
{ "id": "seq1", "seq": [ { "src": [{"in": "source.mp4"}] } ] },
{"sources": ["seq1"]},
{"x": 0, "y": -45, "width": 100, "height": 10, "text": ["Some nice text !"], "size": 60, "fill": "black", "line_width": -2, "line_color": "white"}
]

Insert last two lines of text.txt over video:

[
{ "id": "seq1", "seq": [ { "src": [{"in": "source.mp4"}] } ] },
{"sources": ["seq1"]},
{"x": 0, "y": -40, "width": 100, "height": 10, "text": ["text.txt", 2], "size": 60, "fill": "black", "line_width": -2, "line_color": "white"}
]

Mix two videos with blending:

[
{ "id": "seq1", "seq": [ { "src": [{"in": "source.mp4"}] } ] },
{ "id": "seq2", "seq": [ { "src": [{"in": "source2.mp4"}] } ] },
{"sources": ["seq1", "seq2"], "mix": { "type": "mix"}, "mix_ratio": 0.5 }
]

Side by side videos:

[
{ "id": "seq1", "seq": [ { "src": [{"in": "source1.mp4"}] } ] },
{ "id": "seq2", "seq": [ { "src": [{"in": "source2.mp4"}] } ] },
{"sources": ["seq1"], "x": -25, "y": 0, "width": 50, "height": 100, "volume":0},
{"sources": ["seq2"], "x": 25, "y": 0, "width": 50, "height": 100, "volume":0}
]

Picture in picture video with alpha (source2 can be a video or an image) :

[
{ "id": "seq1", "seq": [ { "src": [{"in": "source1.mp4"}] } ] },
{ "id": "seq2", "seq": [ { "src": [{"in": "source2.mp4"}] } ] },
{"sources": ["seq1"]},
{"sources": ["seq2"], "x": 35, "y": 35, "width": 20, "height": 20, "alpha":0.5}
]

Picture in picture video with shape and alpha:

[
{ "id": "seq1", "seq": [ { "src": [{"in": "source1.mp4"}] } ] },
{ "id": "seq2", "seq": [ { "src": [{"in": "source2.mp4"}] } ] },
{"sources": ["seq1"]},
{"sources": ["seq2"], "x": 35, "y": 35, "width": 20, "height": 20, "alpha":0.5, "shape": "ellipse", "line_width":2, "line_color":"cyan"}
]

Picture in picture video with alpha and rotation along Y axis (perspective texture mapping):

[
{ "id": "seq1", "seq": [ { "src": [{"in": "source1.mp4"}] } ] },
{ "id": "seq2", "seq": [ { "src": [{"in": "source2.mp4"}] } ] },
{"sources": ["seq1"]},
{"sources": ["seq2"], "x": 35, "y": 35, "width": 20, "height": 20, "alpha":0.5, "rotation": "-30", "axis":[0,1,0]}
]

Moving picture in picture video with animated alpha:

[
{ "id": "seq1", "seq": [ { "src": [{"in": "source1.mp4"}] } ] },
{ "id": "seq2", "seq": [ { "src": [{"in": "source2.mp4"}] } ] },
{"sources": ["seq1"]},
{"id": "pip" "sources": ["seq2"], "x": 35, "y": 35, "width": 20, "height": 20, "alpha":0.5},
{"start": 0, "loop": true, "dur": 8, "keys": [0, 0.25, 0.5, 0.75, 1], "anims": [
    {"values": [35, -35, -35, 35, 35], "targets": ["pip@x"]},
    {"values": [35, 35, -35, -35, 35], "targets": ["pip@y"]},
    {"values": [1, 0, 1, 0, 1], "targets": ["logo@alpha"]}
 ]
}
]

Mix two videos with animated slide effect:

[
{ "id": "seq1", "seq": [ { "src": [{"in": "source.mp4"}] } ] },
{ "id": "seq2", "seq": [ { "src": [{"in": "source2.mp4"}] } ] },
{ "id": "scene", "sources": ["seq1", "seq2"], "mix": { "type": "swipe"}, "mix_ratio": 0.5 },
{"start": 0, "loop": true, "dur": 4, "keys": [0, 0.5, 1], "anims": [
    {"values": [1, 0, 1], "targets": ["scene@mix_ratio"]}
 ]
}
]

Fractal-like animated video reuse

[
{ "id": "seq1", "seq": [ { "src": [{"in": "source.mp4"}] } ] },
{ "id": "gr1", "scenes": [
    {"sources": ["seq1"]},
    {"id":"use", "use": "gr1", "rotation": 10, "hscale": 0.9, "vscale": 0.9, "use_depth": 10}
]
},
{ "start": 0, "loop": true, "dur": 2, "keys": [0, 0.5, 1], "anims": [
    {"values": [0, 20, 0], "targets": ["use@use_depth"]}
 ]
}
]