FFmpeg
encode.h
Go to the documentation of this file.
1 /*
2  * generic encoding-related code
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 #ifndef AVCODEC_ENCODE_H
22 #define AVCODEC_ENCODE_H
23 
24 #include "libavutil/frame.h"
25 
26 #include "avcodec.h"
27 #include "packet.h"
28 
29 /**
30  * Used by some encoders as upper bound for the length of headers.
31  * TODO: Use proper codec-specific upper bounds.
32  */
33 #define FF_INPUT_BUFFER_MIN_SIZE 16384
34 
35 /**
36  * Called by encoders to get the next frame for encoding.
37  *
38  * @param frame An empty frame to be filled with data.
39  * @return 0 if a new reference has been successfully written to frame
40  * AVERROR(EAGAIN) if no data is currently available
41  * AVERROR_EOF if end of stream has been reached, so no more data
42  * will be available
43  */
45 
46 /**
47  * Get a buffer for a packet. This is a wrapper around
48  * AVCodecContext.get_encode_buffer() and should be used instead calling get_encode_buffer()
49  * directly.
50  */
51 int ff_get_encode_buffer(AVCodecContext *avctx, AVPacket *avpkt, int64_t size, int flags);
52 
53 /**
54  * Allocate buffers for a frame. Encoder equivalent to ff_get_buffer().
55  */
57 
58 /**
59  * Check AVPacket size and allocate data.
60  *
61  * Encoders of type FF_CODEC_CB_TYPE_ENCODE can use this as a convenience to
62  * obtain a big enough buffer for the encoded bitstream.
63  *
64  * @param avctx the AVCodecContext of the encoder
65  * @param avpkt The AVPacket: on success, avpkt->data will point to a buffer
66  * of size at least `size`; the packet will not be refcounted.
67  * This packet must be initially blank.
68  * @param size an upper bound of the size of the packet to encode
69  * @return non negative on success, negative error code on failure
70  */
71 int ff_alloc_packet(AVCodecContext *avctx, AVPacket *avpkt, int64_t size);
72 
73 /**
74  * Propagate user opaque values from the frame to avctx/pkt as needed.
75  */
77  AVPacket *pkt, const AVFrame *frame);
78 
80  AVFrame *frame, int *got_packet);
81 
82 /**
83  * Add a CPB properties side data to an encoding context.
84  */
86 
87 /**
88  * Rescale from sample rate to AVCodecContext.time_base.
89  */
91  int64_t samples)
92 {
93  if (samples == AV_NOPTS_VALUE)
94  return AV_NOPTS_VALUE;
95  return av_rescale_q(samples, (AVRational){ 1, avctx->sample_rate },
96  avctx->time_base);
97 }
98 
99 #endif /* AVCODEC_ENCODE_H */
AVCodecContext::sample_rate
int sample_rate
samples per second
Definition: avcodec.h:1050
AVFrame
This structure describes decoded (raw) audio or video data.
Definition: frame.h:375
ff_encode_encode_cb
int ff_encode_encode_cb(AVCodecContext *avctx, AVPacket *avpkt, AVFrame *frame, int *got_packet)
Definition: encode.c:247
pkt
AVPacket * pkt
Definition: movenc.c:59
av_rescale_q
int64_t av_rescale_q(int64_t a, AVRational bq, AVRational cq)
Rescale a 64-bit integer by 2 rational numbers.
Definition: mathematics.c:142
AVCPBProperties
This structure describes the bitrate properties of an encoded bitstream.
Definition: defs.h:269
AVRational
Rational number (pair of numerator and denominator).
Definition: rational.h:58
ff_samples_to_time_base
static av_always_inline int64_t ff_samples_to_time_base(const AVCodecContext *avctx, int64_t samples)
Rescale from sample rate to AVCodecContext.time_base.
Definition: encode.h:90
ff_encode_alloc_frame
int ff_encode_alloc_frame(AVCodecContext *avctx, AVFrame *frame)
Allocate buffers for a frame.
Definition: encode.c:817
AVCodecContext::time_base
AVRational time_base
This is the fundamental unit of time (in seconds) in terms of which frame timestamps are represented.
Definition: avcodec.h:544
size
int size
Definition: twinvq_data.h:10344
AV_NOPTS_VALUE
#define AV_NOPTS_VALUE
Undefined timestamp value.
Definition: avutil.h:248
frame.h
packet.h
av_always_inline
#define av_always_inline
Definition: attributes.h:49
ff_encode_get_frame
int ff_encode_get_frame(AVCodecContext *avctx, AVFrame *frame)
Called by encoders to get the next frame for encoding.
Definition: encode.c:204
avcodec.h
frame
these buffered frames must be flushed immediately if a new input produces new the filter must not call request_frame to get more It must just process the frame or queue it The task of requesting more frames is left to the filter s request_frame method or the application If a filter has several the filter must be ready for frames arriving randomly on any input any filter with several inputs will most likely require some kind of queuing mechanism It is perfectly acceptable to have a limited queue and to drop frames when the inputs are too unbalanced request_frame For filters that do not use the this method is called when a frame is wanted on an output For a it should directly call filter_frame on the corresponding output For a if there are queued frames already one of these frames should be pushed If the filter should request a frame on one of its repeatedly until at least one frame has been pushed Return or at least make progress towards producing a frame
Definition: filter_design.txt:264
AVCodecContext
main external API structure.
Definition: avcodec.h:445
ff_alloc_packet
int ff_alloc_packet(AVCodecContext *avctx, AVPacket *avpkt, int64_t size)
Check AVPacket size and allocate data.
Definition: encode.c:61
samples
Filter the word “frame” indicates either a video frame or a group of audio samples
Definition: filter_design.txt:8
ff_get_encode_buffer
int ff_get_encode_buffer(AVCodecContext *avctx, AVPacket *avpkt, int64_t size, int flags)
Get a buffer for a packet.
Definition: encode.c:105
ff_encode_add_cpb_side_data
AVCPBProperties * ff_encode_add_cpb_side_data(AVCodecContext *avctx)
Add a CPB properties side data to an encoding context.
Definition: encode.c:879
AVPacket
This structure stores compressed data.
Definition: packet.h:499
flags
#define flags(name, subs,...)
Definition: cbs_av1.c:474
ff_encode_reordered_opaque
int ff_encode_reordered_opaque(AVCodecContext *avctx, AVPacket *pkt, const AVFrame *frame)
Propagate user opaque values from the frame to avctx/pkt as needed.
Definition: encode.c:234