Specifying input files

Input media files to dash can use the following modifiers  

- #trackID=N: only use the track ID N from the source file  
- #N: only use the track ID N from the source file (mapped to [-tkid](mp4dmx/#tkid))  
- #video: only use the first video track from the source file  
- #audio: only use the first audio track from the source file  
- #Prop=Value: add PID filtering using the same syntax as SID fragments (cf `gpac -h doc`)  
- :id=NAME: set the representation ID to NAME. Reserved value `NULL` disables representation ID for multiplexed inputs. If not set, a default value is computed and all selected tracks from the source will be in the same output multiplex.  
- :dur=VALUE: process VALUE seconds (fraction) from the media. If VALUE is longer than media duration, last sample duration is extended.  
- :period=NAME: set the representation's period to NAME. Multiple periods may be used. Periods appear in the MPD in the same order as specified with this option  
- :BaseURL=NAME: set the BaseURL. Set multiple times for multiple BaseURLs  


__Warning: This does not modify generated files location (see segment template).__  
  

- :bandwidth=VALUE: set the representation's bandwidth to a given value  
- :pdur=VALUE: sets the duration of the associated period to VALUE seconds (fraction) (alias for period_duration:VALUE). This is only used when no input media is specified (remote period insertion), e.g. `:period=X:xlink=Z:pdur=Y`  
- :ddur=VALUE: override target DASH segment duration to VALUE seconds (fraction) for this input (alias for duration:VALUE)  
- :xlink=VALUE: set the xlink value for the period containing this element. Only the xlink declared on the first rep of a period will be used  
- :asID=VALUE: set the AdaptationSet ID to VALUE (unsigned int)  
- :role=VALUE: set the role of this representation (cf DASH spec). Media with different roles belong to different adaptation sets.  
- :desc_p=VALUE: add a descriptor at the Period level.  
- :desc_as=VALUE: add a descriptor at the AdaptationSet level. Two input files with different values will be in different AdaptationSet elements.  
- :desc_as_c=VALUE: add a descriptor at the AdaptationSet level. Value is ignored while creating AdaptationSet elements.  
- :desc_rep=VALUE: add a descriptor at the Representation level. Value is ignored while creating AdaptationSet elements.  
- :sscale: force movie timescale to match media timescale of the first track in the segment.  
- :trackID=N: same as setting fragment `#trackID=`  
- @f1[:args][@fN:args][@@fK:args]: set a filter chain to insert between the source and the dasher. Each filter in the chain is formatted as a regular filter, see [filter doc `gpac -h doc`](filters_general). If several filters are set:  

    - they will be chained in the given order if separated by a single `@`  
    - a new filter chain will be created if separated by a double `@@`. In this case, no representation ID is assigned to the source.  

Example
```
source.mp4:@c=avc:b=1M@@c=avc:b=500k
```
  
This will load a filter chain with two encoders connected to the source and to the dasher.  
Example
```
source.mp4:@c=avc:b=1M@c=avc:b=500k
```
  
This will load a filter chain with the second encoder connected to the output of the first (!!).  
  
_Note: `@f` must be placed after all other options._  
  
_Note: Descriptors value must be a properly formatted XML element(s), value is not checked. Syntax can use `file@FILENAME` to load content from file._