fuchsia.mediacodec

PROTOCOLS

CodecFactory

Defined in fuchsia.mediacodec/codec_factory.fidl

OnCodecList

Response

NameType
codecs vector<CodecDescription>

CreateDecoder

Request

NameType
decoder_params CreateDecoder_Params
decoder request<fuchsia.media/StreamProcessor>

CreateEncoder

Request

NameType
encoder_params CreateEncoder_Params
encoder request<fuchsia.media/StreamProcessor>

STRUCTS

CodecDescription

Defined in fuchsia.mediacodec/codec_factory.fidl

NameTypeDescriptionDefault
codec_type CodecType No default
mime_type string No default
can_stream_bytes_input bool true
can_find_start bool true
can_re_sync bool true
will_report_all_detected_errors bool true
is_hw bool true
split_header_handling bool true

ENUMS

CodecType

Type: uint32

Defined in fuchsia.mediacodec/codec_factory.fidl

NameValueDescription
DECODER 0
ENCODER 1

TABLES

CreateDecoder_Params

Defined in fuchsia.mediacodec/codec_factory.fidl

OrdinalNameTypeDescription
1 input_details fuchsia.media/FormatDetails Input mime type for a decoder. The recognized mime types for now: video/h264 video/vp9 audio/aac input_details.oob_bytes must be an AudioSpecificConfig() as defined by AAC spec.
2 promise_separate_access_units_on_input bool This must be true in order for the client to be permitted to put a timestamp on an input packet, which is in turn required to get any timestamps on any output packets. It is always legal to provide separate Access Units (henceforth AUs) to a decoder, but this boolean must be true for a decoder to accept and propagate timestamp values. This must be true when creating a video encoder, or the CodecFactory channel will close.
3 require_can_stream_bytes_input bool Require that the selected codec be capable of accepting input where AUs are not separated into separate packets. This does not imply that the decoder can find the start of the first AU; for that see require_can_find_start. This does not imply that the decoder can re-sync on its own if the stream data is damaged; for that see require_can_re_sync. If both promise_separate_access_units_on_input and require_can_stream_bytes_input are true, the CodecFactory channel will close. If this is false, the client must feed separate AUs on the fuchsia.ui.input. This must be false for a video encoder, and if true the CodecFactory channel will close. Unless a client demands a decoder capable of taking concatenated AUs (require_can_stream_bytes_input true), the client must feed a decoder separate AUs. This means the client cannot have parts of two separate AUs in the same packet, unless require_can_stream_bytes_input is true.
4 require_can_find_start bool A decoder is allowed to be capable of streaming bytes but not capable of searching for the start of the first usable AU. To require both, set both require_can_stream_bytes_input and require_can_find_start. Setting require_can_find_start without require_can_stream_bytes_input is invalid. With require_can_stream_bytes_input true but require_can_find_start false, the client must start the first packet with the start of an AU, but can send a stream of bytes after that.
5 require_can_re_sync bool On problematic input data, all decoders are expected to at least be able to close the channel rather than getting stuck in a failed and/or broken state. A decoder returned from a request with require_can_re_sync is potentially able to handle damaged input without closing the Codec channel. Such a Codec is encouraged, but not required, to also satisfy requirements of require_report_all_detected_errors.
6 require_report_all_detected_errors bool Sometimes a client would rather fail an overall use of a decoder than fail to notice data corruption. For such scenarios, the client can specify require_report_all_detected_errors. For any codec returned from a request with require_report_all_detected_errors set, on detection of any input data corruption the codec will report in one or more of these ways: * closing the Codec channel * OnStreamFailed() * error_detected_before * error_detected_during If false, a codec may silently skip past corrupted input data. No decoder can detect all corruption, because some corruption can look like valid stream data. This requirement is only to request a codec that is written to attempt to detect _and report_ input stream corruption. This flag is not intended to be 100% bulletproof. If a client needs robust assurance that _all_ detectable stream corruption is _always_ detected, this flag is not enough of a guarantee to achieve that. Since some stream corruption is inherently non-detectable in any case, such a client should consider using stronger techniques upstream to ensure that corruption can be detected with the needed probability very close to 1. This flag being true doesn't imply anything about whether the codec will discard damaged data vs. producing corresponding damaged output. Only that the codec will set error_detected_* bools to true when appropriate. Regardless of this setting, not all timestamp_ish values provided on input are guaranteed to show up on output.
7 require_hw bool If true, require that the returned codec is HW-accelerated.
8 permit_lack_of_split_header_handling bool permit_lack_of_split_header_handling This field is a temporary field that will be going away. TODO(dustingreen): Remove this field once we're down to zero codecs with problems handling split headers. By default, a Codec instance is required to handle "split headers", meaning that a client is allowed to deliver parts of an AU one byte at a time, including parts near the beginning of the AU, and the codec is required to tolerate and handle that properly. However, unfortunately not all codecs properly support split headers. If a client is willing to permit such a codec to be used, the client can set this to true. Clients are not encouraged to set this, but setting it may be necessary to find a codec for some formats _for now_. If a client sets this to true, the client should deliver data of each AU with many contiguous non-split bytes from the start of each AU. The client is not strictly required to deliver one AU at a time, only to ensure that either all the AU bytes are in a single packet or that many bytes at the start of each AU are in a single packet. The specification for how a client should use this and how a client should behave if setting this to true is intentionally vague, because lack of support for header splitting is not ideal, and is expected to be temporary, and all codecs should handle split headers in the long run. The main intent of this field is to avoid giving an innocent client using default value of false here a codec that can't properly handle split headers. This is not an attempt at a mechanism to fully work around a codec that doesn't handle split headers.

CreateEncoder_Params

Defined in fuchsia.mediacodec/codec_factory.fidl

Parameters used to request an encoder.

OrdinalNameTypeDescription
1 input_details fuchsia.media/FormatDetails The format of the uncompressed input data. This field should be a raw mime_type (e.g. 'video/raw') and uncompressed format details for the encoder to use when reading buffers. To be elibigible an encoder must support the input format.
2 require_hw bool If true, require that the returned codec is HW-accelerated.