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FFmpeg/libavcodec/flashsvenc.c
Andreas Rheinhardt 56e9e0273a avcodec/encode: Always use intermediate buffer in ff_alloc_packet2()
Up until now, ff_alloc_packet2() has a min_size parameter:
It is supposed to be a lower bound on the final size of the packet
to allocate. If it is not too far from the upper bound (namely,
if it is at least half the upper bound), then ff_alloc_packet2()
already allocates the final, already refcounted packet; if it is
not, then the packet is not refcounted and its data only points to
a buffer owned by the AVCodecContext (in this case, the packet will
be made refcounted in encode_simple_internal() in libavcodec/encode.c).
The goal of this was to avoid data copies and intermediate buffers
if one has a precise lower bound.

Yet those encoders for which precise lower bounds exist have recently
been switched to ff_get_encode_buffer() (which automatically allocates
final buffers), leaving only two encoders to actually set the min_size
to something else than zero (namely aliaspixenc and hapenc). Both of
these encoders use a very low lower bound that is not helpful in any
nontrivial case.

This commit therefore removes the min_size parameter as well as the
codepath in ff_alloc_packet2() for the allocation of final buffers.
Furthermore, the function has been renamed to ff_alloc_packet() and
moved to encode.h alongside ff_get_encode_buffer().

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
2021-06-08 12:52:50 +02:00

272 lines
8.3 KiB
C

/*
* Flash Screen Video encoder
* Copyright (C) 2004 Alex Beregszaszi
* Copyright (C) 2006 Benjamin Larsson
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/* Encoding development sponsored by http://fh-campuswien.ac.at */
/**
* @file
* Flash Screen Video encoder
* @author Alex Beregszaszi
* @author Benjamin Larsson
*
* A description of the bitstream format for Flash Screen Video version 1/2
* is part of the SWF File Format Specification (version 10), which can be
* downloaded from http://www.adobe.com/devnet/swf.html.
*/
/*
* Encoding ideas: A basic encoder would just use a fixed block size.
* Block sizes can be multiples of 16, from 16 to 256. The blocks don't
* have to be quadratic. A brute force search with a set of different
* block sizes should give a better result than to just use a fixed size.
*
* TODO:
* Don't reencode the frame in brute force mode if the frame is a dupe.
* Speed up. Make the difference check faster.
*/
#include <stdio.h>
#include <stdlib.h>
#include <zlib.h>
#include "avcodec.h"
#include "encode.h"
#include "internal.h"
#include "put_bits.h"
#include "bytestream.h"
typedef struct FlashSVContext {
AVCodecContext *avctx;
uint8_t *previous_frame;
int image_width, image_height;
int block_width, block_height;
uint8_t *encbuffer;
int block_size;
int last_key_frame;
uint8_t tmpblock[3 * 256 * 256];
} FlashSVContext;
static int copy_region_enc(uint8_t *sptr, uint8_t *dptr, int dx, int dy,
int h, int w, int stride, uint8_t *pfptr)
{
int i, j;
uint8_t *nsptr;
uint8_t *npfptr;
int diff = 0;
for (i = dx + h; i > dx; i--) {
nsptr = sptr + i * stride + dy * 3;
npfptr = pfptr + i * stride + dy * 3;
for (j = 0; j < w * 3; j++) {
diff |= npfptr[j] ^ nsptr[j];
dptr[j] = nsptr[j];
}
dptr += w * 3;
}
if (diff)
return 1;
return 0;
}
static av_cold int flashsv_encode_end(AVCodecContext *avctx)
{
FlashSVContext *s = avctx->priv_data;
av_freep(&s->encbuffer);
av_freep(&s->previous_frame);
return 0;
}
static av_cold int flashsv_encode_init(AVCodecContext *avctx)
{
FlashSVContext *s = avctx->priv_data;
s->avctx = avctx;
if (avctx->width > 4095 || avctx->height > 4095) {
av_log(avctx, AV_LOG_ERROR,
"Input dimensions too large, input must be max 4095x4095 !\n");
return AVERROR_INVALIDDATA;
}
s->last_key_frame = 0;
s->image_width = avctx->width;
s->image_height = avctx->height;
s->encbuffer = av_mallocz(s->image_width * s->image_height * 3);
if (!s->encbuffer) {
av_log(avctx, AV_LOG_ERROR, "Memory allocation failed.\n");
return AVERROR(ENOMEM);
}
return 0;
}
static int encode_bitstream(FlashSVContext *s, const AVFrame *p, uint8_t *buf,
int buf_size, int block_width, int block_height,
uint8_t *previous_frame, int *I_frame)
{
PutBitContext pb;
int h_blocks, v_blocks, h_part, v_part, i, j;
int buf_pos, res;
int pred_blocks = 0;
init_put_bits(&pb, buf, buf_size);
put_bits(&pb, 4, block_width / 16 - 1);
put_bits(&pb, 12, s->image_width);
put_bits(&pb, 4, block_height / 16 - 1);
put_bits(&pb, 12, s->image_height);
flush_put_bits(&pb);
buf_pos = 4;
h_blocks = s->image_width / block_width;
h_part = s->image_width % block_width;
v_blocks = s->image_height / block_height;
v_part = s->image_height % block_height;
/* loop over all block columns */
for (j = 0; j < v_blocks + (v_part ? 1 : 0); j++) {
int y_pos = j * block_height; // vertical position in frame
int cur_blk_height = (j < v_blocks) ? block_height : v_part;
/* loop over all block rows */
for (i = 0; i < h_blocks + (h_part ? 1 : 0); i++) {
int x_pos = i * block_width; // horizontal position in frame
int cur_blk_width = (i < h_blocks) ? block_width : h_part;
int ret = Z_OK;
uint8_t *ptr = buf + buf_pos;
/* copy the block to the temp buffer before compression
* (if it differs from the previous frame's block) */
res = copy_region_enc(p->data[0], s->tmpblock,
s->image_height - (y_pos + cur_blk_height + 1),
x_pos, cur_blk_height, cur_blk_width,
p->linesize[0], previous_frame);
if (res || *I_frame) {
unsigned long zsize = 3 * block_width * block_height;
ret = compress2(ptr + 2, &zsize, s->tmpblock,
3 * cur_blk_width * cur_blk_height, 9);
if (ret != Z_OK)
av_log(s->avctx, AV_LOG_ERROR,
"error while compressing block %dx%d\n", i, j);
bytestream_put_be16(&ptr, zsize);
buf_pos += zsize + 2;
ff_dlog(s->avctx, "buf_pos = %d\n", buf_pos);
} else {
pred_blocks++;
bytestream_put_be16(&ptr, 0);
buf_pos += 2;
}
}
}
if (pred_blocks)
*I_frame = 0;
else
*I_frame = 1;
return buf_pos;
}
static int flashsv_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
const AVFrame *pict, int *got_packet)
{
FlashSVContext * const s = avctx->priv_data;
const AVFrame * const p = pict;
uint8_t *pfptr;
int res;
int I_frame = 0;
int opt_w = 4, opt_h = 4;
/* First frame needs to be a keyframe */
if (avctx->frame_number == 0) {
s->previous_frame = av_mallocz(FFABS(p->linesize[0]) * s->image_height);
if (!s->previous_frame) {
av_log(avctx, AV_LOG_ERROR, "Memory allocation failed.\n");
return AVERROR(ENOMEM);
}
I_frame = 1;
}
if (p->linesize[0] < 0)
pfptr = s->previous_frame - (s->image_height - 1) * p->linesize[0];
else
pfptr = s->previous_frame;
/* Check the placement of keyframes */
if (avctx->gop_size > 0 &&
avctx->frame_number >= s->last_key_frame + avctx->gop_size) {
I_frame = 1;
}
if ((res = ff_alloc_packet(avctx, pkt, s->image_width * s->image_height * 3)) < 0)
return res;
pkt->size = encode_bitstream(s, p, pkt->data, pkt->size, opt_w * 16, opt_h * 16,
pfptr, &I_frame);
//save the current frame
if (p->linesize[0] > 0)
memcpy(s->previous_frame, p->data[0], s->image_height * p->linesize[0]);
else
memcpy(s->previous_frame,
p->data[0] + p->linesize[0] * (s->image_height - 1),
s->image_height * FFABS(p->linesize[0]));
//mark the frame type so the muxer can mux it correctly
if (I_frame) {
s->last_key_frame = avctx->frame_number;
ff_dlog(avctx, "Inserting keyframe at frame %d\n", avctx->frame_number);
}
if (I_frame)
pkt->flags |= AV_PKT_FLAG_KEY;
*got_packet = 1;
return 0;
}
const AVCodec ff_flashsv_encoder = {
.name = "flashsv",
.long_name = NULL_IF_CONFIG_SMALL("Flash Screen Video"),
.type = AVMEDIA_TYPE_VIDEO,
.id = AV_CODEC_ID_FLASHSV,
.priv_data_size = sizeof(FlashSVContext),
.init = flashsv_encode_init,
.encode2 = flashsv_encode_frame,
.close = flashsv_encode_end,
.pix_fmts = (const enum AVPixelFormat[]){ AV_PIX_FMT_BGR24, AV_PIX_FMT_NONE },
.caps_internal = FF_CODEC_CAP_INIT_THREADSAFE,
};