We're hiring!

GStreamer buffer flow analyzer

Guillaume Desmottes avatar

Guillaume Desmottes
April 25, 2019

Share this post:

GStreamer's logging system is an incredibly powerful ally when debugging but it can sometimes be a bit daunting to dig through the massive amount of generated logs. I often find myself writing small scripts processing gst logs when debugging. Their goal is generally to automatically extract some specific information or metrics from the generated logs. Such scripts are usually quickly written and quickly disposed once I'm done with my debugging but I've been wondering how I could make them easier to write and to re-use.

gst-log-parser is an attempt to solve these two problems by providing a library parsing GStreamer logs and enabling users to easily build such tools. It's written in Rust and is shipped with a few tools that I wrote to track actual bugs in GStreamer elements and applications.

One of those tool is a buffer flow analyzer which can be used to provide various information regarding the buffers exchanged through your pipeline. It relies on logs generated by the upstream stats tracer, so no modification in GStreamer core or in plugins is required.

First step is to generate the logs, this is easily done by defining these env variables: GST_DEBUG="GST_TRACER:7" GST_DEBUG_FILE=gst.log GST_TRACERS=stats

We can then use flow for example to detect decreasing pts or dts:

cargo run --release --bin flow gst.log check-decreasing-pts

Decreasing pts tsdemux0:audio_0_0042 00:00:02.550852023 < 00:00:02.555653845

Or to detect gaps of at least 100ms in the buffers flow:

cargo run --release --bin flow gst.log gap 100

gap from udpsrc0:src : 00:00:00.100142318 since previous buffer (received: 00:00:02.924532910 previous: 00:00:02.824390592)

It can also be used to draw graphs of the pts/dts produced by each src pad over time:

cargo run --release --bin flow gst.log plot-pts
Graph of the pts/dts produced by each src pad over time.

These are just a few examples of the kind of information we can extract from stats logs. I'll likely add more tools in the future and I'm happy to hear suggestions about other features that would make your life easier when debugging GStreamer.

Visit Guillaume's blog.

Comments (0)

Add a Comment

Allowed tags: <b><i><br>Add a new comment:

Search the newsroom

Latest Blog Posts

Using syzkaller, part 4: Driver fuzzing


Syzkaller is much needed tool for Linux kernel testing and debugging. With some work, it can also be enhanced to find bugs in specific drivers,…

Cross building Rust GStreamer plugins for the Raspberry Pi


Previously, we discussed about how Rust can be a great language for embedded programming. In this article, we'll explain an easy setup to…

Generating MPEG-DASH streams for Open Source adaptive streaming with GStreamer


Adaptive streaming is a technique to provide flexibility and scalability by offering variable bit-rate streams to the client. Here's a quick…

Bifrost meets GNOME: Onward & upward to zero graphics blobs


With only free software, a Mali G31 chip can now run Wayland compositors with zero-copy graphics, including GNOME 3. We can run every scene…

Using regmaps to make Linux drivers more generic


Device drivers can support more revisions and SoC platforms by abstracting away specific hardware interface layouts. Let's examine a specific…

Cross-compiling with gst-build and GStreamer


gst-build is one of the main build systems used by the community to develop the GStreamer platform. In my last blog post, I presented gst-build…

Open Since 2005 logo

We use cookies on this website to ensure that you get the best experience. By continuing to use this website you are consenting to the use of these cookies. To find out more please follow this link.

Collabora Ltd © 2005-2020. All rights reserved. Privacy Notice. Sitemap.