gst-validate-transcoding

gst-validate-transcoding — Tool to test GStreamer transcoding components

Synopsis

gst-validate-transcoding [options...] [INPUT-URI] [OUTPUT-URI]

Description

gst-validate-transcoding is tool to create media files transcoding pipelines running inside the GstValidate monitoring infrastructure.

You can for example transcode any media file to Vorbis audio + VP8 video in a WebM container by doing:

1
gst-validate-transcoding-1.0 file:///./file.ogg file:///.../transcoded.webm -o 'video/webm:video/x-vp8:audio/x-vorbis'

gst-validate-transcoding will list every issue encountered during the execution of the transcoding operation in a human readable report like the one below:

issue : buffer is out of the segment range Detected on theoradec0.srcpad at 0:00:00.096556426 Details : buffer is out of segment and shouldn't be pushed. Timestamp: 0:00:25.000 - duration: 0:00:00.040 Range: 0:00:00.000 - 0:00:04.520 Description : buffer being pushed is out of the current segment's start-stop range. Meaning it is going to be discarded downstream without any use

The return code of the process will be 18 in case a CRITICAL issue has been found.

The encoding profile serialization format

This is the serialization format of a GstEncodingProfile.

Internally the transcoding application uses GstEncodeBin. gst-validate-transcoding-1.0 uses its own serialization format to describe the GstEncodeBin.profile property of the encodebin.

The simplest serialized profile looks like:

1
muxer_source_caps:videoencoder_source_caps:audioencoder_source_caps

For example to encode a stream into a WebM container, with an OGG audio stream and a VP8 video stream, the serialized GstEncodingProfile will look like:

1
video/webm:video/x-vp8:audio/x-vorbis

You can also set the preset name of the encoding profile using the caps+preset_name syntax as in:

1
video/webm:video/x-vp8+youtube-preset:audio/x-vorbis

Moreover, you can set the presence property of an encoding profile using the |presence syntax as in:

1
video/webm:video/x-vp8|1:audio/x-vorbis

This field allows you to specify how many times maximum a GstEncodingProfile can be used inside an encodebin.

You can also use the restriction_caps->encoded_format_caps syntax to specify the restriction caps to be set on a GstEncodingProfile. It corresponds to the restriction GstCaps to apply before the encoder that will be used in the profile. The fields present in restriction caps are properties of the raw stream (that is, before encoding), such as height and width for video and depth and sampling rate for audio. This property does not make sense for muxers.

To force a video stream to be encoded with a Full HD resolution (using WebM as the container format, VP8 as the video codec and Vorbis as the audio codec), you should use:

1
video/webm:video/x-raw,width=1920,height=1080->video/x-vp8:audio/x-vorbis

Some serialized encoding formats examples:

MP3 audio and H264 in MP4:

1
video/quicktime,variant=iso:video/x-h264:audio/mpeg,mpegversion=1,layer=3

Vorbis and theora in OGG:

1
application/ogg:video/x-theora:audio/x-vorbis

AC3 and H264 in MPEG-TS:

1
video/mpegts:video/x-h264:audio/x-ac3

Invocation

gst-validate-transcoding takes and input URI and an output URI, plus a few options to control how transcoding should be tested.

Options

--set-scenario

Let you set a scenario, it can be a full path to a scenario file or the name of the scenario (name of the file without the .scenario extension).

-l, --list-scenarios

List the avalaible scenarios that can be run.

--scenarios-defs-output-file

The output file to store scenarios details. Implies --list-scenario.

-t, --inspect-action-type

Inspect the avalaible action types with which to write scenarios if no parameter passed, it will list all avalaible action types otherwize will print the full description of the wanted types.

--set-configs

Let you set a config scenario. The scenario needs to be set as config. You can specify a list of scenarios separated by :. It will override the GST_VALIDATE_SCENARIO environment variable.

-e, --eos-on-shutdown

If an EOS event should be sent to the pipeline if an interrupt is received, instead of forcing the pipeline to stop. Sending an EOS will allow the transcoding to finish the files properly before exiting.

-r, --force-reencoding

Whether to try to force reencoding, meaning trying to only remux if possible, defaults to TRUE.