FFProbe Bitrate Graph
This project contains a script for plotting the bitrate of an audio or video stream over time. To get the frame bitrate data ffprobe is used from the ffmpeg package. The ffprobe data is streamed to python as xml frame metadata and optionally sorted by frame type. Matplotlib is used to plot the overall bitrate or each frame type on the same graph with lines for the peak and mean bitrates. The resulting bitrate graph can be saved as an image.
Possible outputs are:
- Image types (png, svg, pdf, ...)
- Raw frame data (csv, xml)
Requirements:
- Python >= 3.6
- FFmpeg >= 1.2 with the ffprobe command
- Matplotlib
- PyQt5 or PyQt6 (optional for image file output)
For using the script from source, install the requirements with
pip install -r requirements.txt or use the requirements-dev.txt
for development purposes.
pip install plotbitrate
If you encounter the error message qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "" even though it was found. while running
plotbitrate, then you may need to install your distribution's
libxcb-cursor0 package. If this package is already installed and/or doesn't
resolve the issue, then you can try using QT_DEBUG_PLUGINS=1 plotbitrate input.mkv 2>&1 | grep "No such file" to determine if other libraries are
missing.
The raw frame data can be stored in an xml file with the option -f xml_raw,
which the graph can be plotted from. This is useful if the graph should be
shown multiple times with different options, as the source file doesn't need to
be scanned again.
The option --downscale (or -d) is useful if the video is very long and an
overview of the bitrate fluctuation is sufficient and zooming in is not
necessary. This behavior resembles that of the tool "Bitrate Viewer". With this
option, videos will be shown as a downscaled graph, meaning not every second is
being displayed. Multiple seconds will be grouped together and the max value
will be drawn. This downscaling is not applied when viewing individual frame
types as this would lead to wrong graphs. This behavior can be adjusted with
the --max-display-values option. The default value is 700, meaning that at
most 700 individual seconds/bars are drawn.
You may find it useful to save the raw frame data to a CSV file so the frame
data can be processed using another tool. This turns plotbitrate into more of
a helper tool rather than a visualization tool.
One example may be using gnuplot to show an impulse plot for every single
frame split by frame type. Below is an example gnuplot script that mimics an
earlier version of plotbitrate.
#!/usr/bin/gnuplot -persist
set datafile separator ","
plot "< awk -F, '{if($3 == \"I\") print}' frames.csv" u 1:2 t "I" w impulses lt rgb "red", \
"< awk -F, '{if($3 == \"P\") print}' frames.csv" u 1:2 t "P" w impulses lt rgb "green", \
"< awk -F, '{if($3 == \"B\") print}' frames.csv" u 1:2 t "B" w impulses lt rgb "blue"
The necessary input data can be generated using:
plotbitrate -o frames.csv input.mkv
Show video stream bitrate in a window with progress.
plotbitrate input.mkv
Show downscaled video stream bitrate in a window.
plotbitrate -d input.mkv
Show video stream bitrate for each frame type in a window.
plotbitrate -t input.mkv
Save video stream bitrate to an SVG file.
plotbitrate -o output.svg input.mkv
Show audio stream bitrate in a window.
plotbitrate -s audio input.mkv
Save raw ffproble frame data as xml file.
plotbitrate -f xml_raw -o frames.xml input.mkv
Show bitrate graph from raw xml.
plotbitrate frames.xml
Show the bitrate, but fill the area below the curve with a solid color.
plotbitrate --solid input.mkv
It's possible to specify a custom FFPROBE_PATH in case you don't have it on your PATH or want a custom ffprobe:
# Unix
FFPROBE_PATH=/tmp/ffprobe plotbitrate input.mkv
# Windows
set FFPROBE_PATH=C:\temp\ffmpeg\bin\ffprobe.exe
plotbitrate input.mkv