FFmpeg User Guide

Introduction to FFmpeg

FFmpeg is a collection of open-source multimedia processing tools and libraries. It can parse, convert, encode, decode, filter, mux, and transmit video, audio, subtitles, and metadata.

Common FFmpeg command-line tools include:

The main libraries are:

An FFmpeg processing pipeline can be simplified as follows:

Input file / camera / network stream
                │
                ▼
             Demuxing
                │
                ▼
              Decoding
                │
                ▼
         Video or audio filters
                │
                ▼
              Encoding
                │
                ▼
              Muxing
                │
                ▼
       Output file / network stream

Remuxing skips decoding, filtering, and encoding, and directly copies the compressed streams. It is fast and does not reduce media quality.

Installation and Feature Checks

On Debian or Ubuntu, install the standard FFmpeg package provided by the distribution:

sudo apt update
sudo apt install ffmpeg

Display the version and build configuration:

ffmpeg -version
ffmpeg -buildconf

Display the capabilities supported by the current build:

ffmpeg -formats
ffmpeg -codecs
ffmpeg -encoders
ffmpeg -decoders
ffmpeg -filters
ffmpeg -protocols
ffmpeg -hwaccels

Build options differ between distributions. Before using libx264, libx265, SRT, or a particular network protocol, confirm that the current FFmpeg build includes the corresponding encoder or external library.

Standard FFmpeg packages supplied by distributions normally do not include the rkmpp codecs and rkrga filters described below. Rockchip hardware acceleration requires a suitable ffmpeg-rockchip build.

Basic Command Structure

The basic structure of an FFmpeg command is:

ffmpeg [global options] [input options] -i <input> [output options] <output>

For example:

ffmpeg -hide_banner -i input.mp4 -c:v libx264 -c:a aac output.mp4

Option placement is important:

• Options before -i normally apply to the following input.
• Options before an output file normally apply to that output.
• Different options can be assigned to each input and output.

Common global options:

Inspecting Media Information

4.1 Quick Inspection

ffprobe -hide_banner input.mp4

Alternatively:

ffmpeg -hide_banner -i input.mp4

When no output file is provided, ffmpeg -i exits with an error but still prints input media information. Automated applications should use ffprobe.

4.2 JSON Output

ffprobe \
  -v error \
  -show_format \
  -show_streams \
  -of json \
  input.mp4

Display only the codec, dimensions, and frame rate of the first video stream:

ffprobe \
  -v error \
  -select_streams v:0 \
  -show_entries stream=codec_name,width,height,pix_fmt,r_frame_rate \
  -of default=noprint_wrappers=1 \
  input.mp4

Display the media duration:

ffprobe \
  -v error \
  -show_entries format=duration \
  -of default=noprint_wrappers=1:nokey=1 \
  input.mp4

Common Processing Operations

5.1 Remuxing

Copy the compressed streams from an MP4 container to an MKV container:

ffmpeg -i input.mp4 -map 0 -c copy output.mkv

-c copy does not decode or re-encode streams, so performance is normally limited by storage I/O. The target container must support the original video, audio, and subtitle formats.

5.2 Software Transcoding

Convert to H.264 video and AAC audio:

ffmpeg \
  -i input.mkv \
  -c:v libx264 \
  -preset medium \
  -crf 23 \
  -c:a aac \
  -b:a 192k \
  output.mp4

• preset controls the tradeoff between encoding speed and compression efficiency; it does not directly represent image quality.
• crf controls constant quality. With x264, lower values produce higher quality and larger files.
• libx264 and libx265 require FFmpeg to be built with the corresponding external libraries.

5.3 Stream Selection

Select the first video stream and the second audio stream:

ffmpeg \
  -i input.mkv \
  -map 0:v:0 \
  -map 0:a:1 \
  -c copy \
  output.mkv

Continue processing even if the requested audio stream is missing:

ffmpeg -i input.mp4 -map 0:v:0 -map 0:a:0? -c copy output.mp4

The ? marks the mapping as optional.

5.4 Extracting a Segment

Start at one minute and output 30 seconds:

ffmpeg \
  -ss 00:01:00 \
  -i input.mp4 \
  -t 30 \
  -c copy \
  clip.mp4

With -c copy, copying can only begin at a nearby keyframe, so the start point may not be exact. Re-encode when frame-accurate trimming is required:

ffmpeg \
  -ss 00:01:00 \
  -i input.mp4 \
  -t 30 \
  -c:v libx264 \
  -crf 23 \
  -c:a aac \
  clip-accurate.mp4

5.5 Software Scaling, Cropping, and Rotation

Scale proportionally to 720p:

ffmpeg -i input.mp4 -vf 'scale=-2:720' -c:v libx264 -crf 23 -c:a copy output-720p.mp4

Crop the center to 1280x720:

ffmpeg \
  -i input.mp4 \
  -vf "crop=1280:720:(iw-ow)/2:(ih-oh)/2" \
  -c:v libx264 \
  -crf 23 \
  -c:a copy \
  output-crop.mp4

Rotate clockwise by 90 degrees:

ffmpeg -i input.mp4 -vf 'transpose=clock' -c:v libx264 -crf 23 -c:a copy output-rotate.mp4

5.6 Screenshots

Extract one frame at 10 seconds:

ffmpeg -ss 10 -i input.mp4 -frames:v 1 screenshot.png

Output one image every five seconds:

ffmpeg -i input.mp4 -vf 'fps=1/5' 'frame-%05d.jpg'

5.7 Audio Processing

Extract an AAC audio stream without re-encoding:

ffmpeg -i input.mp4 -vn -c:a copy output.m4a

Convert to 48 kHz stereo AAC:

ffmpeg \
  -i input.mp4 \
  -vn \
  -ar 48000 \
  -ac 2 \
  -c:a aac \
  -b:a 192k \
  output.m4a

Adjust the volume:

ffmpeg -i input.wav -af 'volume=1.5' output.wav

5.8 Concatenating Multiple Files

When the containers, codecs, time bases, and stream parameters of several files match, use the concat demuxer. Create list.txt:

file 'part-01.mp4'
file 'part-02.mp4'
file 'part-03.mp4'

Concatenate the files:

ffmpeg -f concat -safe 0 -i list.txt -c copy output.mp4

If the file parameters differ, transcode them to matching formats first, or re-encode them with the concat filter.

5.9 Network Streaming

Stream a file to an RTMP server at its native playback speed:

ffmpeg \
  -re \
  -i input.mp4 \
  -c:v libx264 \
  -preset veryfast \
  -b:v 4M \
  -maxrate 4M \
  -bufsize 8M \
  -g 60 \
  -c:a aac \
  -b:a 128k \
  -f flv \
  rtmp://server.example.com/live/stream

Publish to an RTSP server:

ffmpeg \
  -re \
  -i input.mp4 \
  -c:v libx264 \
  -preset veryfast \
  -c:a aac \
  -f rtsp \
  rtsp://server.example.com/live/stream

-re reads a file at its native timing, which is useful for simulating a live source. Do not use it for cameras, sound devices, or other inputs that are already real-time.

Common Output Options

Create an MP4 suitable for web playback:

ffmpeg \
  -i input.mp4 \
  -c:v libx264 \
  -crf 23 \
  -c:a aac \
  -movflags +faststart \
  output-web.mp4

General Troubleshooting

Enable detailed logging:

ffmpeg -loglevel verbose -i input.mp4 <output-options> output.mp4

Save a complete log for issue reporting:

ffmpeg -report -i input.mp4 <output-options> output.mp4

Overview

ffmpeg-rockchip is an FFmpeg branch extended for Rockchip platforms. It uses MPP (Media Process Platform) for hardware video encoding and decoding, and RGA (2D Raster Graphic Acceleration) for scaling, cropping, rotation, pixel-format conversion, and layer composition.

A typical hardware processing pipeline is:

Input → MPP hardware decoder → DRM_PRIME/DMA-BUF
                                  │
                                  ▼
                           RGA image processing
                                  │
                                  ▼
                           MPP hardware encoder → Output

Keeping video frames as drm_prime hardware frames reduces data copies between CPU memory and hardware video buffers, lowering CPU usage and DDR bandwidth consumption.

ffmpeg-rockchip is an unofficial FFmpeg branch. Refer to the project's README and license files for usage and open-source licensing requirements.

Supported Features

MPP hardware decoders:

MPP hardware encoders:

RGA hardware filters:

The presence of a codec in the source does not mean that every Rockchip SoC implements the corresponding hardware capability. Maximum resolution, frame rate, bit depth, profile, level, and concurrent stream count depend on the target SoC's datasheet, TRM, and BSP.

Runtime Requirements

ffmpeg-rockchip requires a Rockchip BSP/vendor kernel. The project has mainly been tested with Linux kernels 5.10 and 6.1.

Build and runtime requirements include:

• Rockchip MPP 1.3.9 or later.
• A librga version matching the BSP.
• libdrm with DRM_PRIME/DMA-BUF support.
• Permission to access the MPP, RGA, and DRM device nodes.

Common device nodes include:

/dev/mpp_service
/dev/rga
/dev/dri/
/dev/dma_heap/

Check the device nodes:

ls -l /dev/mpp_service /dev/rga /dev/dri /dev/dma_heap 2>/dev/null

The FFmpeg user normally needs to belong to the video or render group associated with these device nodes:

id
sudo usermod -aG video,render "$USER"

The group change takes effect after logging in again. Production systems should configure permissions with udev rules instead of permanently using chmod 777.

Building and Verifying

Check the dependencies:

pkg-config --modversion libdrm
pkg-config --modversion rockchip_mpp
pkg-config --modversion librga

Get and build the source code:

git clone https://github.com/nyanmisaka/ffmpeg-rockchip.git
cd ffmpeg-rockchip

./configure \
  --prefix=/usr/local \
  --enable-version3 \
  --enable-libdrm \
  --enable-rkmpp \
  --enable-rkrga \
  --enable-shared \
  --disable-static

make -j$(nproc)
sudo make install
sudo ldconfig

Confirm that the expected FFmpeg binary is being used:

command -v ffmpeg
ffmpeg -version

Check the Rockchip hardware features:

ffmpeg -hide_banner -hwaccels | grep -i rkmpp
ffmpeg -hide_banner -decoders | grep rkmpp
ffmpeg -hide_banner -encoders | grep rkmpp
ffmpeg -hide_banner -filters  | grep rkrga

If these entries are missing, the command may be using the distribution's standard FFmpeg binary, or MPP/RGA support may not have been enabled successfully during the build.

Usage Examples

5.1 Hardware Decoding Test

ffmpeg \
  -hwaccel rkmpp \
  -hwaccel_output_format drm_prime \
  -i input.mp4 \
  -an -f null -

The decoder can also be selected explicitly:

ffmpeg -c:v h264_rkmpp -i input-h264.mp4 -an -f null -
ffmpeg -c:v hevc_rkmpp -i input-hevc.mp4 -an -f null -

5.2 H.264 Hardware Encoding

ffmpeg \
  -i input.mp4 \
  -c:v h264_rkmpp \
  -rc_mode VBR \
  -b:v 8M \
  -maxrate 10M \
  -g 60 \
  -c:a copy \
  output-h264.mp4

5.3 HEVC Hardware Encoding

ffmpeg \
  -i input.mp4 \
  -c:v hevc_rkmpp \
  -rc_mode VBR \
  -b:v 6M \
  -maxrate 8M \
  -g 60 \
  -c:a copy \
  output-hevc.mp4

The H.264 and HEVC encoders support VBR, CBR, CQP, and AVBR rate-control modes. Display the complete options supported by the installed build with:

ffmpeg -hide_banner -h encoder=h264_rkmpp
ffmpeg -hide_banner -h encoder=hevc_rkmpp

5.4 Zero-Copy Scaling and Transcoding

ffmpeg \
  -hwaccel rkmpp \
  -hwaccel_output_format drm_prime \
  -i input.mp4 \
  -vf 'scale_rkrga=w=1920:h=1080:format=nv12' \
  -c:v h264_rkmpp \
  -rc_mode VBR \
  -b:v 8M \
  -c:a copy \
  output-1080p.mp4

This command uses MPP decoding, RGA scaling, and MPP encoding. Video frames are passed between hardware blocks through DRM_PRIME/DMA-BUF.

Display the filter help before using other RGA features:

ffmpeg -hide_banner -h filter=scale_rkrga
ffmpeg -hide_banner -h filter=vpp_rkrga
ffmpeg -hide_banner -h filter=overlay_rkrga

Common Issues

Display detailed logs:

ffmpeg -loglevel verbose <other-options>
dmesg | grep -Ei 'mpp|rga|vpu|rkvdec|rkvenc'

References:

• ffmpeg-rockchip
• Rockchip MPP
• Rockchip RGA