Encode with an auto-generated bitrate ladder
Warning
Azure Media Services will be retired June 30th, 2024. For more information, see the AMS Retirement Guide.
Tip
Want to generate thumbnails, stitch two videos together, subclip a video or rotate it (among other things)? You can find Media Services sample code on the Samples page.
Overview
This article explains how to use the Standard Encoder in Media Services to encode an input video into an auto-generated bitrate ladder (bitrate-resolution pairs) based on the input resolution and bitrate. This built-in encoder setting, or preset, will never exceed the input resolution and bitrate. For example, if the input is 720p at 3 Mbps, output remains 720p at best, and will start at rates lower than 3 Mbps.
Encoding for streaming
When you use the AdaptiveStreaming or H265AdaptiveStreaming preset in Transform, you get an output that is suitable for delivery via streaming protocols like HLS and DASH. When using one of these two presets, the service intelligently determines how many video layers to generate and at what bitrate and resolution. The output content contains MP4 files where AAC-encoded audio and either H.264-encoded video (in the case of the AdaptiveStreaming preset) or H.265/HEVC (in the case of the H265AdaptiveStreaming preset). The output MP4 files are non-interleaved.
Output
This section shows three examples of the output video layers produced by the Media Services encoder as a result of encoding with the AdaptiveStreaming(H.264) or the H265AdaptiveStreaming (HEVC) presets. In all cases, the output contains an audio-only MP4 file with stereo audio encoded at 128 kbps.
Example 1
Source with height "1080" and framerate "29.970" produces 6 video layers:
| Layer | Height | Width | Bitrate (kbps) |
|---|---|---|---|
| 1 | 1080 | 1920 | 6780 |
| 2 | 720 | 1280 | 3520 |
| 3 | 540 | 960 | 2210 |
| 4 | 360 | 640 | 1150 |
| 5 | 270 | 480 | 720 |
| 6 | 180 | 320 | 380 |
Example 2
Source with height "720" and framerate "23.970" produces 5 video layers:
| Layer | Height | Width | Bitrate (kbps) |
|---|---|---|---|
| 1 | 720 | 1280 | 2940 |
| 2 | 540 | 960 | 1850 |
| 3 | 360 | 640 | 960 |
| 4 | 270 | 480 | 600 |
| 5 | 180 | 320 | 320 |
Example 3
Source with height "360" and framerate "29.970" produces 3 video layers:
| Layer | Height | Width | Bitrate (kbps) |
|---|---|---|---|
| 1 | 360 | 640 | 700 |
| 2 | 270 | 480 | 440 |
| 3 | 180 | 320 | 230 |
Content-aware encoding comparison
The content-aware encoding presets offer a better solution over the adaptive streaming presets by analyzing the source content prior to deciding the right set of output bitrates and resolutions to use in the ladder. Test the content-aware encoding presets first before using the more static and fixed ladder provided by the adaptive bitrate streaming presets.
Encoding samples
See the extensive list of Encoding samples.
Get help and support
You can contact Media Services with questions or follow our updates by one of the following methods:
- Q & A
- Stack Overflow. Tag questions with
azure-media-services. - @MSFTAzureMedia or use @AzureSupport to request support.
- Open a support ticket through the Azure portal.