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

Integrating libcamera into PipeWire

11/09/2020

PipeWire continues to evolve with the recent integration of libcamera, a library to support complex cameras. In this blog post, I'll explain…

Pushing pixels to your Chromebook

31/08/2020

A high-level introduction of the Linux graphics stack, how it is used within ChromeOS, and the work done to improve software rendering (while…

Using the Linux kernel's Case-insensitive feature in Ext4

27/08/2020

Last year, a (controversial) feature was added to the Linux kernel to support optimized case-insensitive file name lookups in the Ext4 filesystem.…

Panfrost performance counters with Perfetto

21/08/2020

We have now integrated Mali GPU hardware counters supported by Panfrost with Perfetto's tracing SDK, unlocking all-in-one graphics-aware…

Paving the way for high bitrate video streaming with GStreamer's RTP elements

20/08/2020

Key performance improvements and fixes to GStreamer's RTP stack have landed in GStreamer 1.18, due in the coming months. The latest enhancements…

Understanding computer vision & AI, part 1

13/08/2020

Following our recent presentation at OSSummit, many showed interest in learning more about solving real-world problems with computer vision.…

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.