Learn how to trim a video segment from a single source asset using the RMS API. This guide provides API reference documentation, workflow steps, and troubleshooting guidance for video trimming.

In this article:

Trimming concept

API workflow 

Construct a trimming request

Parameters

Responses

Considerations

Troubleshooting

Before you begin:

• Authenticate using the RMS API Authentication.
• Upload a media file to use as the trim source (use RMS Console or your SDK).

Trimming concept

Video trimming extracts a single continuous segment from one source asset by specifying a start and end time. Stitching, by contrast, joins segments from one or more sources into a new timeline.

Common use cases:

• Remove unwanted footage from the beginning or end of a recording.
• Extract a highlight clip from a longer video.

Trimming runs as part of job processing, based on the preset.

API workflow 

Use the following steps to build a trimming job:

1. Define the trim range

• Reference the source asset in the input parameters.
• Set timing parameters:
  • Set start time - when to begin the trimmed output.
  • Set end time - when to end the trimmed output. Example: A source video has a total duration of 60 seconds. Setting a start time of PT10S and an end time of PT45S produces a trimmed output 35 seconds long.

2. Create and specify the output asset

• Create the asset for the output result. Use the Asset - Create Or Update API call.
• Specify the output asset name where your trimmed video will be saved.

3. Submit the trimming job

The system automatically:

• Trims the source between the specified start and end time.
• Processes the trimmed segment using your selected transform, applying its encoding settings.
• Saves the final trimmed video to the specified asset.

The output inherits encoding settings from your selected transform, including the media format.

Construct a trimming request 

Use this reference when building your API calls to trim a video.

PUT https://{{api-endpoint}}/subscriptions/{subscriptionId}/resourceGroups/{resourceGroupName}/providers/Microsoft.Media/mediaServices/{accountName}/transforms/{transformName}/jobs/{jobName}?api-version={{api-version}}

Request URL structure:

• api-endpoint: Placeholder for your RMS API endpoint.
• subscriptionId: This is your Azure subscription ID, a unique identifier for your Azure subscription.
• resourceGroup: The name of the resource group where your Media Services account is located.
• accountName: This is the name of your Media Services account.
• transformName: Select a transform - the predefined processing settings (resolution, bitrate, etc.).
• jobName: The job name.
• api-version={{api-version}}: This specifies the version of the AMS API you used. Any valid version number will work for your requests. Example: api-version=2018-07-01.

Request body:

{
    "properties": {
        "input": {
            "@odata.type": "#Microsoft.Media.JobInputAsset",
            "AssetName": "your-asset-name",
            "start": {
                "@odata.type": "#Microsoft.Media.AbsoluteClipTime",
                "Time": "PT10S"
            },
            "end": {
                "@odata.type": "#Microsoft.Media.AbsoluteClipTime",
                "Time": "PT45S"
            }
        },
        "outputs": [
            {
                "@odata.type": "#Microsoft.Media.JobOutputAsset",
                "assetName": "trim1-name"
            }
        ],
        "priority": "Normal"
    }
}

Trimming uses a single JobInputAsset as the input property, since it operates on one source and does not need the JobInputSequence wrapper that stitching uses to order multiple inputs.

Parameters

Request body parameters used in the trimming request:

Responses

Sample response

Status code: 201

Response body:

{
    "properties": {
        "created": "2025-06-18T15:38:21.2990342Z",
        "state": "Queued",
        "input": {
            "assetName": "your-asset-name",
            "start": {
                "time": "PT10S",
                "@odata.type": "#Microsoft.Media.AbsoluteClipTime"
            },
            "end": {
                "time": "PT45S",
                "@odata.type": "#Microsoft.Media.AbsoluteClipTime"
            },
            "inputDefinitions": [],
            "@odata.type": "#Microsoft.Media.JobInputAsset"
        },
        "lastModified": "2025-06-18T15:38:21.2990342Z",
        "outputs": [
            {
                "assetName": "trim1-name",
                "@odata.type": "#Microsoft.Media.JobOutputAsset",
                "state": "Queued",
                "progress": 0,
                "label": "BuiltInStandardEncoderPreset_0"
            }
        ],
        "priority": "Normal"
    },
    "systemData": {
        "createdBy": "system",
        "createdByType": "Application",
        "createdAt": "2025-06-18T15:38:21.2990342Z",
        "lastModifiedBy": "system",
        "lastModifiedByType": "Application",
        "lastModifiedAt": "2025-06-18T15:38:21.2990342Z"
    },
    "id": "/subscriptions/00000000-0000-0000-0000-000000000000/resourceGroups/mrg-yourresourceGroupName/providers/Microsoft.Media/mediaServices/default/transforms/StandardEncoder-AdaptiveStreaming/jobs/your-job-name",
    "name": "your-job-name",
    "type": "Microsoft.Media/mediaservices/transforms/jobs"
}

Considerations

General

• Without start and end time values, the job processes the entire source video and does not trim it.
• Trimming accepts a single input asset. To combine segments from multiple sources, or multiple segments from the same source, use stitching instead.
• RMS trims video only; audio-only files are not supported for trimming.  

Preset and processing behavior

• Trimming works with any transform created using the BuiltInStandardEncoderPreset presets, or the StandardEncoderPreset custom presets.
• The preset determines whether trimming copies or re-encodes the segment.  Copying skips re-encoding, so the trim finishes in seconds, no matter how long the segment is. Re-encoding takes longer - the longer the segment, the longer the job takes.

Recorded live streams

• For recorded ABR live streams, the trimmed output's quality renditions may not all start at the exact same timestamp - a carryover from the source recording, not a trimming error.

Troubleshooting

Encountering issues with video trimming jobs? Here are common problems and their solutions to restore your content processing:

• Verify that the end time does not exceed the source video duration. The job fails with a validation error if the end time is greater than the video duration.
  • Example: Asset has 45s in total timeline with start: PT10S, end: PT50S (end is 5s longer than the timeline).
• Check that the start time is less than the end time.
  • Example: Asset with start: PT30S, end: PT10S (end is before start).
• Ensure timing values use a valid ISO 8601 format with no negative values.

To view job details, including trim boundaries, make a GET request to retrieve the job information.

Jobs with Error status include a complete error stack to help you address specific issues. If you still need assistance, contact Ravnur.

See more

• RMS API: Media stitching
• API reference: Jobs
• API reference: Transforms
• RMS Console: Process media