Common interface for video decoders (e.g. H264Decoder, H264DecoderESP32S3 - CodecH264.h/CodecH264ESP32S3.h) - standardizes lifecycle (begin()/end()), the Print target decoded pictures are written to, and the pixel format they're written in (setVideoFormat()), on top of VideoOutput's write()/flush() (the encoded-bitstream input side, inherited unchanged). Concrete decoders may still expose their own additional config knobs beyond this shared surface.
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#include <CodecVideo.h>
Common interface for video decoders (e.g. H264Decoder, H264DecoderESP32S3 - CodecH264.h/CodecH264ESP32S3.h) - standardizes lifecycle (begin()/end()), the Print target decoded pictures are written to, and the pixel format they're written in (setVideoFormat()), on top of VideoOutput's write()/flush() (the encoded-bitstream input side, inherited unchanged). Concrete decoders may still expose their own additional config knobs beyond this shared surface.
- Author
- Phil Schatzmann
- Copyright
- GPLv3
◆ ~VideoDecoder()
◆ begin()
◆ codecFormat()
◆ end()
◆ flush()
◆ getWriteTimeMs()
| virtual uint32_t getWriteTimeMs |
( |
| ) |
const |
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inlinevirtualinherited |
◆ hadOutput()
| virtual bool hadOutput |
( |
| ) |
const |
|
inlinevirtualinherited |
True if the most recent write()+flush() call actually produced a displayable picture - default true, matching every synchronous decoder (H264Decoder, MJPEGDecoder, ...), which always decodes and pushes pixels fully within that one call. Override this only if your decoder can legitimately accept/decode a frame's bytes without emitting a picture during that same call - e.g. MPGDecoder, whose B-picture display-order reordering can hold a just-decoded picture back and instead emit an earlier one (or nothing at all) from a given write(), see its own override. Used by PacedVideoOutput to avoid counting/timing a call that did no real rendering work as a rendered frame - without this, its outputFPS()/frameCountI()/ frameCountP()/avgFrameMs() would overcount for such a decoder.
Reimplemented in MPGDecoder.
◆ isKeyFrame()
| virtual bool isKeyFrame |
( |
const uint8_t * |
data, |
|
|
size_t |
len |
|
) |
| |
|
inlinevirtualinherited |
True if data (one complete encoded frame, as handed to write()) is a keyframe/sync-sample - self-contained, decodable without any earlier frame. Used e.g. by PacedVideoOutput to decide which frames are safe to drop, and whether it's safe to resume decoding after abandoning a backlog (see its own class comment). Default false: a plain VideoOutput doesn't know or care about codec structure - override this in a decoder for the bitstream format it actually parses (see H264Decoder/H264DecoderESP32S3's isH264KeyFrame()-based override, MPGDecoder's isMpeg1KeyFrame()- based one). Getting this right matters beyond bookkeeping: a target whose frames are never recognized as keyframes can leave a caller like PacedVideoOutput unable to ever resume after a resync.
Reimplemented in PacedVideoOutput, H264Decoder, H264DecoderESP32S3< Alloc >, MJPEGDecoder, MPGDecoder, MultiVideoDecoder, and OutputFPSMeter.
◆ isValid()
| virtual bool isValid |
( |
const uint8_t * |
data, |
|
|
size_t |
len |
|
) |
| |
|
inlinevirtual |
True if data (the start of an access unit, as handed to write()) looks like this decoder's own bitstream format - content-sniffing, not a guarantee (see the concrete class for exactly what's checked). Used by MultiVideoDecoder to auto-select a registered decoder when no VideoInfoSource answer is available (see its own class comment); not otherwise part of the write()/flush() decode path. Default false, matching VideoOutput::isKeyFrame()'s own default - a decoder not meant to be auto-detected this way (e.g. a hardware-accelerated backend not registered by default, still usable via an explicit VideoInfoSource-based selection) simply never overrides it.
Reimplemented in H264Decoder, MJPEGDecoder, and MPGDecoder.
◆ setOutput() [1/2]
| virtual void setOutput |
( |
Print & |
out | ) |
|
|
pure virtual |
◆ setOutput() [2/2]
◆ setSkipRender()
| virtual void setSkipRender |
( |
bool |
skip | ) |
|
|
inlinevirtualinherited |
Hint to skip the expensive part of displaying the next frame(s) (e.g. the panel refresh) while still accepting and fully processing write() calls - used to recover from falling behind the playback schedule without breaking a codec's decode state (e.g. H.264 inter-prediction reference chain, which requires every frame to still be decoded even if it's never shown). Default no-op: implementations that can't skip rendering cheaply just ignore it and always render.
Reimplemented in MultiVideoDecoder, OutputFPSMeter, OutputTinyGPU, PacedVideoOutput, and VideoFrameMeter.
◆ setVideoFormat()
Selects the pixel format written to setOutput()'s target - e.g. VideoFormat::RGB565 (the common TFT wire format), RGB666/RGB888 for higher color depth displays, or I420 to pass the decoded planes through unconverted. Not every decoder backend supports every value (e.g. RGB666/RGB888 are TinyH264-only, not available on the esp_h264 backend) - unsupported values are logged and ignored (the previously selected format stays in effect); see the concrete class for exactly which ones it supports. Call before begin().
Implemented in H264Decoder, H264DecoderESP32S3< Alloc >, MJPEGDecoder, MPGDecoder, and MultiVideoDecoder.
◆ setVideoInfoSource()
◆ totalDecodeMs()
| virtual uint64_t totalDecodeMs |
( |
| ) |
const |
|
inlinevirtualinherited |
Optional: sum of time (ms) spent purely decoding (excluding any surrounding convert/render/SPI work a subclass's write() also does) since begin() - see H264Decoder's own override for the only current implementation. Default 0: only meaningful for a decoder that separates decode time from render time internally: PacedVideoOutput:: logTo() prints a decode-vs-render split under "avg decode ms:" only when this returns nonzero.
Reimplemented in H264Decoder, and MultiVideoDecoder.
◆ videoInfo()
◆ write()
| virtual size_t write |
( |
const uint8_t * |
data, |
|
|
size_t |
len |
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) |
| |
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pure virtualinherited |
Implemented in MuxerAVI, MuxerMP4, MuxerMPG, H264Decoder, H264DecoderESP32S3< Alloc >, MJPEGDecoder, MPGDecoder, MultiVideoDecoder, OutputFPSMeter, OutputOpenCV, OutputTFT_eSPI, OutputTinyGPU, PacedVideoOutput, and VideoFrameMeter.
The documentation for this class was generated from the following file:
