* @}
*/
+/**
+ * @ingroup libavc
+ * @defgroup lavc_encdec send/receive encoding and decoding API overview
+ * @{
+ *
+ * The avcodec_send_packet()/avcodec_receive_frame()/avcodec_send_frame()/
+ * avcodec_receive_packet() functions provide an encode/decode API, which
+ * decouples input and output.
+ *
+ * The API is very similar for encoding/decoding and audio/video, and works as
+ * follows:
+ * - Set up and open the AVCodecContext as usual.
+ * - Send valid input:
+ * - For decoding, call avcodec_send_packet() to give the decoder raw
+ * compressed data in an AVPacket.
+ * - For encoding, call avcodec_send_frame() to give the decoder an AVFrame
+ * containing uncompressed audio or video.
+ * In both cases, it is recommended that AVPackets and AVFrames are
+ * refcounted, or libavcodec might have to copy the input data. (libavformat
+ * always returns refcounted AVPackets, and av_frame_get_buffer() allocates
+ * refcounted AVFrames.)
+ * - Receive output in a loop. Periodically call one of the avcodec_receive_*()
+ * functions and process their output:
+ * - For decoding, call avcodec_receive_frame(). On success, it will return
+ * an AVFrame containing uncompressed audio or video data.
+ * - For encoding, call avcodec_receive_packet(). On success, it will return
+ * an AVPacket with a compressed frame.
+ * Repeat this call until it returns AVERROR(EAGAIN) or an error. The
+ * AVERROR(EAGAIN) return value means that new input data is required to
+ * return new output. In this case, continue with sending input. For each
+ * input frame/packet, the codec will typically return 1 output frame/packet,
+ * but it can also be 0 or more than 1.
+ *
+ * At the beginning of decoding or encoding, the codec might accept multiple
+ * input frames/packets without returning a frame, until its internal buffers
+ * are filled. This situation is handled transparently if you follow the steps
+ * outlined above.
+ *
+ * End of stream situations. These require "flushing" (aka draining) the codec,
+ * as the codec might buffer multiple frames or packets internally for
+ * performance or out of necessity (consider B-frames).
+ * This is handled as follows:
+ * - Instead of valid input, send NULL to the avcodec_send_packet() (decoding)
+ * or avcodec_send_frame() (encoding) functions. This will enter draining
+ * mode.
+ * - Call avcodec_receive_frame() (decoding) or avcodec_receive_packet()
+ * (encoding) in a loop until AVERROR_EOF is returned. The functions will
+ * not return AVERROR(EAGAIN), unless you forgot to enter draining mode.
+ * - Before decoding can be resumed again, the codec has to be reset with
+ * avcodec_flush_buffers().
+ *
+ * Using the API as outlined above is highly recommended. But it is also
+ * possible to call functions outside of this rigid schema. For example, you can
+ * call avcodec_send_packet() repeatedly without calling
+ * avcodec_receive_frame(). In this case, avcodec_send_packet() will succeed
+ * until the codec's internal buffer has been filled up (which is typically of
+ * size 1 per output frame, after initial input), and then reject input with
+ * AVERROR(EAGAIN). Once it starts rejecting input, you have no choice but to
+ * read at least some output.
+ *
+ * Not all codecs will follow a rigid and predictable dataflow; the only
+ * guarantee is that an AVERROR(EAGAIN) return value on a send/receive call on
+ * one end implies that a receive/send call on the other end will succeed. In
+ * general, no codec will permit unlimited buffering of input or output.
+ *
+ * This API replaces the following legacy functions:
+ * - avcodec_decode_video2() and avcodec_decode_audio4():
+ * Use avcodec_send_packet() to feed input to the decoder, then use
+ * avcodec_receive_frame() to receive decoded frames after each packet.
+ * Unlike with the old video decoding API, multiple frames might result from
+ * a packet. For audio, splitting the input packet into frames by partially
+ * decoding packets becomes transparent to the API user. You never need to
+ * feed an AVPacket to the API twice.
+ * Additionally, sending a flush/draining packet is required only once.
+ * - avcodec_encode_video2()/avcodec_encode_audio2():
+ * Use avcodec_send_frame() to feed input to the encoder, then use
+ * avcodec_receive_packet() to receive encoded packets.
+ * Providing user-allocated buffers for avcodec_receive_packet() is not
+ * possible.
+ * - The new API does not handle subtitles yet.
+ *
+ * Mixing new and old function calls on the same AVCodecContext is not allowed,
+ * and will result in undefined behavior.
+ *
+ * Some codecs might require using the new API; using the old API will return
+ * an error when calling it.
+ * @}
+ */
+
/**
* @defgroup lavc_core Core functions/structures.
* @ingroup libavc
* the decoded frame is cropped before being output or lowres is enabled.
*
* @note Those field may not match the value of the last
- * AVFrame outputted by avcodec_decode_video2 due frame
+ * AVFrame outputted by avcodec_receive_frame() due frame
* reordering.
*
* - encoding: unused
* May be overridden by the decoder if it knows better.
*
* @note This field may not match the value of the last
- * AVFrame outputted by avcodec_decode_video2 due frame
+ * AVFrame outputted by avcodec_receive_frame() due frame
* reordering.
*
* - encoding: Set by user.
* Otherwise, the decoded frames must not be freed by the caller and are
* only valid until the next decode call.
*
+ * This is always automatically enabled if avcodec_receive_frame() is used.
+ *
* - encoding: unused
* - decoding: set by the caller before avcodec_open2().
*/
int *got_packet_ptr);
int (*decode)(AVCodecContext *, void *outdata, int *outdata_size, AVPacket *avpkt);
int (*close)(AVCodecContext *);
+ /**
+ * Decode/encode API with decoupled packet/frame dataflow. The API is the
+ * same as the avcodec_ prefixed APIs (avcodec_send_frame() etc.), except
+ * that:
+ * - never called if the codec is closed or the wrong type,
+ * - AVPacket parameter change side data is applied right before calling
+ * AVCodec->send_packet,
+ * - if AV_CODEC_CAP_DELAY is not set, drain packets or frames are never sent,
+ * - only one drain packet is ever passed down (until the next flush()),
+ * - a drain AVPacket is always NULL (no need to check for avpkt->size).
+ */
+ int (*send_frame)(AVCodecContext *avctx, const AVFrame *frame);
+ int (*send_packet)(AVCodecContext *avctx, const AVPacket *avpkt);
+ int (*receive_frame)(AVCodecContext *avctx, AVFrame *frame);
+ int (*receive_packet)(AVCodecContext *avctx, AVPacket *avpkt);
/**
* Flush buffers.
* Will be called when seeking
* @warning This function is not thread safe!
*
* @note Always call this function before using decoding routines (such as
- * @ref avcodec_decode_video2()).
+ * @ref avcodec_receive_frame()).
*
* @code
* avcodec_register_all();
* @return A negative error code is returned if an error occurred during
* decoding, otherwise the number of bytes consumed from the input
* AVPacket is returned.
+ *
+* @deprecated Use avcodec_send_packet() and avcodec_receive_frame().
*/
+attribute_deprecated
int avcodec_decode_audio4(AVCodecContext *avctx, AVFrame *frame,
int *got_frame_ptr, const AVPacket *avpkt);
* @param[in,out] got_picture_ptr Zero if no frame could be decompressed, otherwise, it is nonzero.
* @return On error a negative value is returned, otherwise the number of bytes
* used or zero if no frame could be decompressed.
+ *
+ * @deprecated Use avcodec_send_packet() and avcodec_receive_frame().
*/
+attribute_deprecated
int avcodec_decode_video2(AVCodecContext *avctx, AVFrame *picture,
int *got_picture_ptr,
const AVPacket *avpkt);
int *got_sub_ptr,
AVPacket *avpkt);
+/**
+ * Supply raw packet data as input to a decoder.
+ *
+ * Internally, this call will copy relevant AVCodecContext fields, which can
+ * influence decoding per-packet, and apply them when the packet is actually
+ * decoded. (For example AVCodecContext.skip_frame, which might direct the
+ * decoder to drop the frame contained by the packet sent with this function.)
+ *
+ * @warning The input buffer, avpkt->data must be AV_INPUT_BUFFER_PADDING_SIZE
+ * larger than the actual read bytes because some optimized bitstream
+ * readers read 32 or 64 bits at once and could read over the end.
+ *
+ * @warning Do not mix this API with the legacy API (like avcodec_decode_video2())
+ * on the same AVCodecContext. It will return unexpected results now
+ * or in future libavcodec versions.
+ *
+ * @note The AVCodecContext MUST have been opened with @ref avcodec_open2()
+ * before packets may be fed to the decoder.
+ *
+ * @param avctx codec context
+ * @param[in] avpkt The input AVPacket. Usually, this will be a single video
+ * frame, or several complete audio frames.
+ * Ownership of the packet remains with the caller, and the
+ * decoder will not write to the packet. The decoder may create
+ * a reference to the packet data (or copy it if the packet is
+ * not reference-counted).
+ * Unlike with older APIs, the packet is always fully consumed,
+ * and if it contains multiple frames (e.g. some audio codecs),
+ * will require you to call avcodec_receive_frame() multiple
+ * times afterwards before you can send a new packet.
+ * It can be NULL (or an AVPacket with data set to NULL and
+ * size set to 0); in this case, it is considered a flush
+ * packet, which signals the end of the stream. Sending the
+ * first flush packet will return success. Subsequent ones are
+ * unnecessary and will return AVERROR_EOF. If the decoder
+ * still has frames buffered, it will return them after sending
+ * a flush packet.
+ *
+ * @return 0 on success, otherwise negative error code:
+ * AVERROR(EAGAIN): input is not accepted right now - the packet must be
+ * resent after trying to read output
+ * AVERROR_EOF: the decoder has been flushed, and no new packets can
+ * be sent to it (also returned if more than 1 flush
+ * packet is sent)
+ * AVERROR(EINVAL): codec not opened, it is an encoder, or requires flush
+ * AVERROR(ENOMEM): failed to add packet to internal queue, or similar
+ * other errors: legitimate decoding errors
+ */
+int avcodec_send_packet(AVCodecContext *avctx, const AVPacket *avpkt);
+
+/**
+ * Return decoded output data from a decoder.
+ *
+ * @param avctx codec context
+ * @param frame This will be set to a reference-counted video or audio
+ * frame (depending on the decoder type) allocated by the
+ * decoder. Note that the function will always call
+ * av_frame_unref(frame) before doing anything else.
+ *
+ * @return
+ * 0: success, a frame was returned
+ * AVERROR(EAGAIN): output is not available right now - user must try
+ * to send new input
+ * AVERROR_EOF: the decoder has been fully flushed, and there will be
+ * no more output frames
+ * AVERROR(EINVAL): codec not opened, or it is an encoder
+ * other negative values: legitimate decoding errors
+ */
+int avcodec_receive_frame(AVCodecContext *avctx, AVFrame *frame);
+
+/**
+ * Supply a raw video or audio frame to the encoder. Use avcodec_receive_packet()
+ * to retrieve buffered output packets.
+ *
+ * @param avctx codec context
+ * @param[in] frame AVFrame containing the raw audio or video frame to be encoded.
+ * Ownership of the frame remains with the caller, and the
+ * encoder will not write to the frame. The encoder may create
+ * a reference to the frame data (or copy it if the frame is
+ * not reference-counted).
+ * It can be NULL, in which case it is considered a flush
+ * packet. This signals the end of the stream. If the encoder
+ * still has packets buffered, it will return them after this
+ * call. Once flushing mode has been entered, additional flush
+ * packets are ignored, and sending frames will return
+ * AVERROR_EOF.
+ *
+ * For audio:
+ * If AV_CODEC_CAP_VARIABLE_FRAME_SIZE is set, then each frame
+ * can have any number of samples.
+ * If it is not set, frame->nb_samples must be equal to
+ * avctx->frame_size for all frames except the last.
+ * The final frame may be smaller than avctx->frame_size.
+ * @return 0 on success, otherwise negative error code:
+ * AVERROR(EAGAIN): input is not accepted right now - the frame must be
+ * resent after trying to read output packets
+ * AVERROR_EOF: the encoder has been flushed, and no new frames can
+ * be sent to it
+ * AVERROR(EINVAL): codec not opened, refcounted_frames not set, it is a
+ * decoder, or requires flush
+ * AVERROR(ENOMEM): failed to add packet to internal queue, or similar
+ * other errors: legitimate decoding errors
+ */
+int avcodec_send_frame(AVCodecContext *avctx, const AVFrame *frame);
+
+/**
+ * Read encoded data from the encoder.
+ *
+ * @param avctx codec context
+ * @param avpkt This will be set to a reference-counted packet allocated by the
+ * encoder. Note that the function will always call
+ * av_frame_unref(frame) before doing anything else.
+ * @return 0 on success, otherwise negative error code:
+ * AVERROR(EAGAIN): output is not available right now - user must try
+ * to send input
+ * AVERROR_EOF: the encoder has been fully flushed, and there will be
+ * no more output packets
+ * AVERROR(EINVAL): codec not opened, or it is an encoder
+ * other errors: legitimate decoding errors
+ */
+int avcodec_receive_packet(AVCodecContext *avctx, AVPacket *avpkt);
+
+
/**
* @defgroup lavc_parsing Frame parsing
* @{
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