# ForwardingExtractor
# ForwardingExtractor
Artifact:[androidx.media3:media3-extractor](https://developer.android.com/jetpack/androidx/releases/media3)
[View Source](https://cs.android.com/search?q=file:androidx/media3/extractor/ForwardingExtractor.java+class:androidx.media3.extractor.ForwardingExtractor)
*** ** * ** ***
Kotlin\|[Java](https://developer.android.com/reference/androidx/media3/extractor/ForwardingExtractor "View this page in Java")
```
@UnstableApi
class ForwardingExtractor : Extractor
```
*** ** * ** ***
An overridable[Extractor](https://developer.android.com/reference/kotlin/androidx/media3/extractor/Extractor)implementation which forwards all methods to another[Extractor](https://developer.android.com/reference/kotlin/androidx/media3/extractor/Extractor).
## Summary
| ### Public constructors |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| [ForwardingExtractor](https://developer.android.com/reference/kotlin/androidx/media3/extractor/ForwardingExtractor#ForwardingExtractor(androidx.media3.extractor.Extractor))`(delegate: `[Extractor](https://developer.android.com/reference/kotlin/androidx/media3/extractor/Extractor)`!)` |
| ### Public functions |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `(`[Mutable](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin.collections/-mutable-list/index.html)`)`[List](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin.collections/-list/index.html)`<`[SniffFailure](https://developer.android.com/reference/kotlin/androidx/media3/extractor/SniffFailure)`!>!` | [getSniffFailureDetails](https://developer.android.com/reference/kotlin/androidx/media3/extractor/ForwardingExtractor#getSniffFailureDetails())`()` Returns additional details about the last call to[sniff](https://developer.android.com/reference/kotlin/androidx/media3/extractor/Extractor#sniff(androidx.media3.extractor.ExtractorInput)). |
| [Extractor](https://developer.android.com/reference/kotlin/androidx/media3/extractor/Extractor)`!` | [getUnderlyingImplementation](https://developer.android.com/reference/kotlin/androidx/media3/extractor/ForwardingExtractor#getUnderlyingImplementation())`()` Returns the 'real'`Extractor`implementation if this is a delegating instance, or` this`if this instance does the extraction directly without delegating (the default behaviour). |
| [Unit](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html) | [init](https://developer.android.com/reference/kotlin/androidx/media3/extractor/ForwardingExtractor#init(androidx.media3.extractor.ExtractorOutput))`(output: `[ExtractorOutput](https://developer.android.com/reference/kotlin/androidx/media3/extractor/ExtractorOutput)`!)` Initializes the extractor with an[ExtractorOutput](https://developer.android.com/reference/kotlin/androidx/media3/extractor/ExtractorOutput). |
| [Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html) | `@`[Extractor.ReadResult](https://developer.android.com/reference/kotlin/androidx/media3/extractor/Extractor.ReadResult) [read](https://developer.android.com/reference/kotlin/androidx/media3/extractor/ForwardingExtractor#read(androidx.media3.extractor.ExtractorInput,androidx.media3.extractor.PositionHolder))`(input: `[ExtractorInput](https://developer.android.com/reference/kotlin/androidx/media3/extractor/ExtractorInput)`!, seekPosition: `[PositionHolder](https://developer.android.com/reference/kotlin/androidx/media3/extractor/PositionHolder)`!)` Extracts data read from a provided[ExtractorInput](https://developer.android.com/reference/kotlin/androidx/media3/extractor/ExtractorInput). |
| [Unit](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html) | [release](https://developer.android.com/reference/kotlin/androidx/media3/extractor/ForwardingExtractor#release())`()` Releases all kept resources. |
| [Unit](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html) | [seek](https://developer.android.com/reference/kotlin/androidx/media3/extractor/ForwardingExtractor#seek(long,long))`(position: `[Long](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-long/index.html)`, timeUs: `[Long](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-long/index.html)`)` Notifies the extractor that a seek has occurred. |
| [Boolean](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-boolean/index.html) | [sniff](https://developer.android.com/reference/kotlin/androidx/media3/extractor/ForwardingExtractor#sniff(androidx.media3.extractor.ExtractorInput))`(input: `[ExtractorInput](https://developer.android.com/reference/kotlin/androidx/media3/extractor/ExtractorInput)`!)` Returns whether this extractor can extract samples from the[ExtractorInput](https://developer.android.com/reference/kotlin/androidx/media3/extractor/ExtractorInput), which must provide data from the start of the stream. |
| ### Inherited Constants |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| From[androidx.media3.extractor.Extractor](https://developer.android.com/reference/kotlin/androidx/media3/extractor/Extractor) |-------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | `const `[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html) | [RESULT_CONTINUE](https://developer.android.com/reference/kotlin/androidx/media3/extractor/Extractor#RESULT_CONTINUE())` = 0` Returned by[read](https://developer.android.com/reference/kotlin/androidx/media3/extractor/Extractor#read(androidx.media3.extractor.ExtractorInput,androidx.media3.extractor.PositionHolder))if the[ExtractorInput](https://developer.android.com/reference/kotlin/androidx/media3/extractor/ExtractorInput)passed to the next[read](https://developer.android.com/reference/kotlin/androidx/media3/extractor/Extractor#read(androidx.media3.extractor.ExtractorInput,androidx.media3.extractor.PositionHolder))is required to provide data continuing from the position in the stream reached by the returning call. | | `const `[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html) | [RESULT_END_OF_INPUT](https://developer.android.com/reference/kotlin/androidx/media3/extractor/Extractor#RESULT_END_OF_INPUT())` = -1` Returned by[read](https://developer.android.com/reference/kotlin/androidx/media3/extractor/Extractor#read(androidx.media3.extractor.ExtractorInput,androidx.media3.extractor.PositionHolder))if the end of the[ExtractorInput](https://developer.android.com/reference/kotlin/androidx/media3/extractor/ExtractorInput)was reached. | | `const `[Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html) | [RESULT_SEEK](https://developer.android.com/reference/kotlin/androidx/media3/extractor/Extractor#RESULT_SEEK())` = 1` Returned by[read](https://developer.android.com/reference/kotlin/androidx/media3/extractor/Extractor#read(androidx.media3.extractor.ExtractorInput,androidx.media3.extractor.PositionHolder))if the[ExtractorInput](https://developer.android.com/reference/kotlin/androidx/media3/extractor/ExtractorInput)passed to the next[read](https://developer.android.com/reference/kotlin/androidx/media3/extractor/Extractor#read(androidx.media3.extractor.ExtractorInput,androidx.media3.extractor.PositionHolder))is required to provide data starting from a specified position in the stream. | |
## Public constructors
### ForwardingExtractor
```
ForwardingExtractor(delegate: Extractor!)
```
## Public functions
### getSniffFailureDetails
```
fun getSniffFailureDetails(): (Mutable)List!
```
Returns additional details about the last call to[sniff](https://developer.android.com/reference/kotlin/androidx/media3/extractor/Extractor#sniff(androidx.media3.extractor.ExtractorInput)). The returned list may be empty if no additional details are available, or the last[sniff](https://developer.android.com/reference/kotlin/androidx/media3/extractor/Extractor#sniff(androidx.media3.extractor.ExtractorInput))call returned`
true`.
This only contains details that were discovered before[sniff](https://developer.android.com/reference/kotlin/androidx/media3/extractor/Extractor#sniff(androidx.media3.extractor.ExtractorInput))returned`
false`, it is not an exhaustive list of issues which, if resolved, would cause the file to be successfully sniffed.
### getUnderlyingImplementation
```
fun getUnderlyingImplementation(): Extractor!
```
Returns the 'real'`Extractor`implementation if this is a delegating instance, or`
this`if this instance does the extraction directly without delegating (the default behaviour).
`Extractor`implementations that operate by delegating to another`Extractor`should override this method to return that delegate.
### init
```
fun init(output: ExtractorOutput!): Unit
```
Initializes the extractor with an[ExtractorOutput](https://developer.android.com/reference/kotlin/androidx/media3/extractor/ExtractorOutput). Called at most once.
| Parameters |
|--------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------|
| `output: `[ExtractorOutput](https://developer.android.com/reference/kotlin/androidx/media3/extractor/ExtractorOutput)`!` | An[ExtractorOutput](https://developer.android.com/reference/kotlin/androidx/media3/extractor/ExtractorOutput)to receive extracted data. |
### read
```
@Extractor.ReadResult
fun read(input: ExtractorInput!, seekPosition: PositionHolder!): Int
```
Extracts data read from a provided[ExtractorInput](https://developer.android.com/reference/kotlin/androidx/media3/extractor/ExtractorInput). Must not be called before[init](https://developer.android.com/reference/kotlin/androidx/media3/extractor/Extractor#init(androidx.media3.extractor.ExtractorOutput)).
A single call to this method will block until some progress has been made, but will not block for longer than this. Hence each call will consume only a small amount of input data.
In the common case,[RESULT_CONTINUE](https://developer.android.com/reference/kotlin/androidx/media3/extractor/Extractor#RESULT_CONTINUE())is returned to indicate that the[ExtractorInput](https://developer.android.com/reference/kotlin/androidx/media3/extractor/ExtractorInput)passed to the next read is required to provide data continuing from the position in the stream reached by the returning call. If the extractor requires data to be provided from a different position, then that position is set in`seekPosition`and[RESULT_SEEK](https://developer.android.com/reference/kotlin/androidx/media3/extractor/Extractor#RESULT_SEEK())is returned. If the extractor reached the end of the data provided by the[ExtractorInput](https://developer.android.com/reference/kotlin/androidx/media3/extractor/ExtractorInput), then[RESULT_END_OF_INPUT](https://developer.android.com/reference/kotlin/androidx/media3/extractor/Extractor#RESULT_END_OF_INPUT())is returned.
When this method throws an[IOException](https://developer.android.com/reference/java/io/IOException.html), extraction may continue by providing an[ExtractorInput](https://developer.android.com/reference/kotlin/androidx/media3/extractor/ExtractorInput)with an unchanged[read position](https://developer.android.com/reference/kotlin/androidx/media3/extractor/ExtractorInput#getPosition())to a subsequent call to this method.
| Parameters |
|------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `input: `[ExtractorInput](https://developer.android.com/reference/kotlin/androidx/media3/extractor/ExtractorInput)`!` | The[ExtractorInput](https://developer.android.com/reference/kotlin/androidx/media3/extractor/ExtractorInput)from which data should be read. |
| `seekPosition: `[PositionHolder](https://developer.android.com/reference/kotlin/androidx/media3/extractor/PositionHolder)`!` | If[RESULT_SEEK](https://developer.android.com/reference/kotlin/androidx/media3/extractor/Extractor#RESULT_SEEK())is returned, this holder is updated to hold the position of the required data. |
| Returns |
|-----------------------------------------------------------------------------|------------------------------------------------------|
| [Int](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html) | One of the`RESULT_`values defined in this interface. |
| Throws |
|-----------------------------------------------------------------------------------------|---------------------------------------------------------|
| [java.io.IOException](https://developer.android.com/reference/java/io/IOException.html) | If an error occurred reading from or parsing the input. |
### release
```
fun release(): Unit
```
Releases all kept resources.
### seek
```
fun seek(position: Long, timeUs: Long): Unit
```
Notifies the extractor that a seek has occurred.
Following a call to this method, the[ExtractorInput](https://developer.android.com/reference/kotlin/androidx/media3/extractor/ExtractorInput)passed to the next invocation of[read](https://developer.android.com/reference/kotlin/androidx/media3/extractor/Extractor#read(androidx.media3.extractor.ExtractorInput,androidx.media3.extractor.PositionHolder))is required to provide data starting from`
position`in the stream. Valid random access positions are the start of the stream and positions that can be obtained from any[SeekMap](https://developer.android.com/reference/kotlin/androidx/media3/extractor/SeekMap)passed to the[ExtractorOutput](https://developer.android.com/reference/kotlin/androidx/media3/extractor/ExtractorOutput).
| Parameters |
|-------------------------------------------------------------------------------------------|-----------------------------------------------------------------|
| `position: `[Long](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-long/index.html) | The byte offset in the stream from which data will be provided. |
| `timeUs: `[Long](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-long/index.html) | The seek time in microseconds. |
### sniff
```
fun sniff(input: ExtractorInput!): Boolean
```
Returns whether this extractor can extract samples from the[ExtractorInput](https://developer.android.com/reference/kotlin/androidx/media3/extractor/ExtractorInput), which must provide data from the start of the stream.
If`true`is returned, the`input`'s reading position may have been modified. Otherwise, only its peek position may have been modified.
| Parameters |
|-----------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------|
| `input: `[ExtractorInput](https://developer.android.com/reference/kotlin/androidx/media3/extractor/ExtractorInput)`!` | The[ExtractorInput](https://developer.android.com/reference/kotlin/androidx/media3/extractor/ExtractorInput)from which data should be peeked/read. |
| Returns |
|-------------------------------------------------------------------------------------|-----------------------------------------------------|
| [Boolean](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-boolean/index.html) | Whether this extractor can read the provided input. |
| Throws |
|-----------------------------------------------------------------------------------------|----------------------------------------------|
| [java.io.IOException](https://developer.android.com/reference/java/io/IOException.html) | If an error occurred reading from the input. |