# Step B: Format the source media
Format the source media

Make sure that the source media meets the requirements.

## Format requirements


You must format the source media according to the CMAF Ingest (Interface-1) version 1.2 specification. 

The following table identifies specific requirements for Elemental Inference.


| Characteristic | Requirement | 
| --- | --- | 
|  Media fragments  |  Fragmented CMAF Ingest containerized media fragments  | 
|  MovieFragmentBox  |  One per segment  | 
|  Initialization segment: naming  |  Include an initialization segment with each stream, as follows: [\[See the AWS documentation website for more details\]](http://docs.aws.amazon.com/elemental-inference/latest/userguide/source-format.html)  | 
|  Media segments: naming  |  Media segments after the initialization segment must following this naming pattern: `Streams default-<type>.<ext>/Segment(<sequence-number>)` Where: <type> is video or audio <ext> is cmfv or cmfa <sequence-number> must increase monotonically, although it doesn't have to be contiguous. Each sequence number must match the sequence number in the MovieFragmentHeader box. For example: `Streams default-video.cmfv/Segment(<sequence-number>)`  | 
|  End of Stream indicator  |  The last media segment in the session must be: [\[See the AWS documentation website for more details\]](http://docs.aws.amazon.com/elemental-inference/latest/userguide/source-format.html) If you can't signal the end of stream in this way, there is a workaround. See [Step C: Deliver the source media](deliver-source.md).  | 

## Example


The following code shows how to use FFMPG to format the media to follow these requirements. The commands demux, segment, and containerize the video and audio. Note the `-init_seg_name` and `-media_seg_name` lines

```
$ mkdir 'Streams(default-video.cmfv)'
$ ffmpeg -i input.mp4 \
-map 0:v:0 -c:v libx264 \
    -profile:v main -pix_fmt yuv420p \
    -g 30 -keyint_min 30 -sc_threshold 0 \
    -force_key_frames 'expr:gte(t,n_forced*1)' \
    -f dash -seg_duration 1 -use_timeline 0 \
    -use_template 1 -remove_at_exit 0  \
    -init_seg_name 'Streams(default-video.cmfv)/InitializationSegment' \
    -media_seg_name 'Streams(default-video.cmfv)/Segment($Number%09d$)' \
    'video.mpd'

$ mkdir 'Streams(default-audio.cmfa)'$ ffmpeg -i input.mp4 \
    -map 0:a:0 -c:a aac -ar 48000 -ac 2 \
    -f dash -seg_duration 1 -use_timeline 0 \
    -use_template 1 -remove_at_exit 0 \
    -init_seg_name 'Streams(default-audio.cmfa)/InitializationSegment' \
    -media_seg_name 'Streams(default-audio.cmfa)/Segment($Number%09d$)' \
    'audio.mpd'
```