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ffmpeg/libavformat/rtpdec_jpeg.c
Andreas Rheinhardt 1d333c1547 avcodec/jpegtables: Unavpriv MJPEG-tables 
There are seven MJPEG-tables, five small (1x12, 4x17) and two
not small (2x162). These are all avpriv, despite this not being
worthwhile due to the overhead of exporting a symbol: The total
overhead for each symbol consists of two entries in .dynsym (24B each),
one entry in the importing library's .rela.dyn (24B) and one in .got
(8B) as well as 2x2B for symbol versions and 4B for symbol hashes
in the exporting library; in addition to that, the name of the symbol
is included in both exporting and importing libraries, using 2x210 bytes
in this case.
(The above numbers are for a x64 Elf/Linux/GNU system. Other platforms
will give different numbers.)

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
2022-01-04 13:16:50 +01:00

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/*
* RTP JPEG-compressed Video Depacketizer, RFC 2435
* Copyright (c) 2012 Samuel Pitoiset
*
* 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
*/
#include "avformat.h"
#include "avio_internal.h"
#include "rtpdec.h"
#include "rtpdec_formats.h"
#include "libavutil/intreadwrite.h"
#include "libavcodec/jpegtables.h"
#include "libavcodec/mjpeg.h"
#include "libavcodec/bytestream.h"
/**
* RTP/JPEG specific private data.
*/
struct PayloadContext {
AVIOContext *frame; ///< current frame buffer
uint32_t timestamp; ///< current frame timestamp
int hdr_size; ///< size of the current frame header
uint8_t qtables[128][128];
uint8_t qtables_len[128];
};
static const uint8_t default_quantizers[128] = {
/* luma table */
16, 11, 12, 14, 12, 10, 16, 14,
13, 14, 18, 17, 16, 19, 24, 40,
26, 24, 22, 22, 24, 49, 35, 37,
29, 40, 58, 51, 61, 60, 57, 51,
56, 55, 64, 72, 92, 78, 64, 68,
87, 69, 55, 56, 80, 109, 81, 87,
95, 98, 103, 104, 103, 62, 77, 113,
121, 112, 100, 120, 92, 101, 103, 99,
/* chroma table */
17, 18, 18, 24, 21, 24, 47, 26,
26, 47, 99, 66, 56, 66, 99, 99,
99, 99, 99, 99, 99, 99, 99, 99,
99, 99, 99, 99, 99, 99, 99, 99,
99, 99, 99, 99, 99, 99, 99, 99,
99, 99, 99, 99, 99, 99, 99, 99,
99, 99, 99, 99, 99, 99, 99, 99,
99, 99, 99, 99, 99, 99, 99, 99
};
static void jpeg_close_context(PayloadContext *jpeg)
{
ffio_free_dyn_buf(&jpeg->frame);
}
static int jpeg_create_huffman_table(PutByteContext *p, int table_class,
int table_id, const uint8_t *bits_table,
const uint8_t *value_table)
{
int i, n = 0;
bytestream2_put_byte(p, table_class << 4 | table_id);
for (i = 1; i <= 16; i++) {
n += bits_table[i];
bytestream2_put_byte(p, bits_table[i]);
}
for (i = 0; i < n; i++) {
bytestream2_put_byte(p, value_table[i]);
}
return n + 17;
}
static void jpeg_put_marker(PutByteContext *pbc, int code)
{
bytestream2_put_byte(pbc, 0xff);
bytestream2_put_byte(pbc, code);
}
static int jpeg_create_header(uint8_t *buf, int size, uint32_t type, uint32_t w,
uint32_t h, const uint8_t *qtable, int nb_qtable,
int dri)
{
PutByteContext pbc;
uint8_t *dht_size_ptr;
int dht_size, i;
bytestream2_init_writer(&pbc, buf, size);
/* Convert from blocks to pixels. */
w <<= 3;
h <<= 3;
/* SOI */
jpeg_put_marker(&pbc, SOI);
/* JFIF header */
jpeg_put_marker(&pbc, APP0);
bytestream2_put_be16(&pbc, 16);
bytestream2_put_buffer(&pbc, "JFIF", 5);
bytestream2_put_be16(&pbc, 0x0102);
bytestream2_put_byte(&pbc, 0);
bytestream2_put_be16(&pbc, 1);
bytestream2_put_be16(&pbc, 1);
bytestream2_put_byte(&pbc, 0);
bytestream2_put_byte(&pbc, 0);
if (dri) {
jpeg_put_marker(&pbc, DRI);
bytestream2_put_be16(&pbc, 4);
bytestream2_put_be16(&pbc, dri);
}
/* DQT */
jpeg_put_marker(&pbc, DQT);
bytestream2_put_be16(&pbc, 2 + nb_qtable * (1 + 64));
for (i = 0; i < nb_qtable; i++) {
bytestream2_put_byte(&pbc, i);
/* Each table is an array of 64 values given in zig-zag
* order, identical to the format used in a JFIF DQT
* marker segment. */
bytestream2_put_buffer(&pbc, qtable + 64 * i, 64);
}
/* DHT */
jpeg_put_marker(&pbc, DHT);
dht_size_ptr = pbc.buffer;
bytestream2_put_be16(&pbc, 0);
dht_size = 2;
dht_size += jpeg_create_huffman_table(&pbc, 0, 0,ff_mjpeg_bits_dc_luminance,
ff_mjpeg_val_dc);
dht_size += jpeg_create_huffman_table(&pbc, 0, 1, ff_mjpeg_bits_dc_chrominance,
ff_mjpeg_val_dc);
dht_size += jpeg_create_huffman_table(&pbc, 1, 0, ff_mjpeg_bits_ac_luminance,
ff_mjpeg_val_ac_luminance);
dht_size += jpeg_create_huffman_table(&pbc, 1, 1, ff_mjpeg_bits_ac_chrominance,
ff_mjpeg_val_ac_chrominance);
AV_WB16(dht_size_ptr, dht_size);
/* SOF0 */
jpeg_put_marker(&pbc, SOF0);
bytestream2_put_be16(&pbc, 17); /* size */
bytestream2_put_byte(&pbc, 8); /* bits per component */
bytestream2_put_be16(&pbc, h);
bytestream2_put_be16(&pbc, w);
bytestream2_put_byte(&pbc, 3); /* number of components */
bytestream2_put_byte(&pbc, 1); /* component number */
bytestream2_put_byte(&pbc, (2 << 4) | (type ? 2 : 1)); /* hsample/vsample */
bytestream2_put_byte(&pbc, 0); /* matrix number */
bytestream2_put_byte(&pbc, 2); /* component number */
bytestream2_put_byte(&pbc, 1 << 4 | 1); /* hsample/vsample */
bytestream2_put_byte(&pbc, nb_qtable == 2 ? 1 : 0); /* matrix number */
bytestream2_put_byte(&pbc, 3); /* component number */
bytestream2_put_byte(&pbc, 1 << 4 | 1); /* hsample/vsample */
bytestream2_put_byte(&pbc, nb_qtable == 2 ? 1 : 0); /* matrix number */
/* SOS */
jpeg_put_marker(&pbc, SOS);
bytestream2_put_be16(&pbc, 12);
bytestream2_put_byte(&pbc, 3);
bytestream2_put_byte(&pbc, 1);
bytestream2_put_byte(&pbc, 0);
bytestream2_put_byte(&pbc, 2);
bytestream2_put_byte(&pbc, 17);
bytestream2_put_byte(&pbc, 3);
bytestream2_put_byte(&pbc, 17);
bytestream2_put_byte(&pbc, 0);
bytestream2_put_byte(&pbc, 63);
bytestream2_put_byte(&pbc, 0);
/* Return the length in bytes of the JPEG header. */
return bytestream2_tell_p(&pbc);
}
static void create_default_qtables(uint8_t *qtables, uint8_t q)
{
int factor = q;
int i;
uint16_t S;
factor = av_clip(q, 1, 99);
if (q < 50)
S = 5000 / factor;
else
S = 200 - factor * 2;
for (i = 0; i < 128; i++) {
int val = (default_quantizers[i] * S + 50) / 100;
/* Limit the quantizers to 1 <= q <= 255. */
val = av_clip(val, 1, 255);
qtables[i] = val;
}
}
static int jpeg_parse_packet(AVFormatContext *ctx, PayloadContext *jpeg,
AVStream *st, AVPacket *pkt, uint32_t *timestamp,
const uint8_t *buf, int len, uint16_t seq,
int flags)
{
uint8_t type, q, width, height;
const uint8_t *qtables = NULL;
uint16_t qtable_len;
uint32_t off;
int ret, dri = 0;
if (len < 8) {
av_log(ctx, AV_LOG_ERROR, "Too short RTP/JPEG packet.\n");
return AVERROR_INVALIDDATA;
}
/* Parse the main JPEG header. */
off = AV_RB24(buf + 1); /* fragment byte offset */
type = AV_RB8(buf + 4); /* id of jpeg decoder params */
q = AV_RB8(buf + 5); /* quantization factor (or table id) */
width = AV_RB8(buf + 6); /* frame width in 8 pixel blocks */
height = AV_RB8(buf + 7); /* frame height in 8 pixel blocks */
buf += 8;
len -= 8;
if (type & 0x40) {
if (len < 4) {
av_log(ctx, AV_LOG_ERROR, "Too short RTP/JPEG packet.\n");
return AVERROR_INVALIDDATA;
}
dri = AV_RB16(buf);
buf += 4;
len -= 4;
type &= ~0x40;
}
if (type > 1) {
avpriv_report_missing_feature(ctx, "RTP/JPEG type %"PRIu8, type);
return AVERROR_PATCHWELCOME;
}
/* Parse the quantization table header. */
if (off == 0) {
/* Start of JPEG data packet. */
uint8_t new_qtables[128];
uint8_t hdr[1024];
if (q > 127) {
uint8_t precision;
if (len < 4) {
av_log(ctx, AV_LOG_ERROR, "Too short RTP/JPEG packet.\n");
return AVERROR_INVALIDDATA;
}
/* The first byte is reserved for future use. */
precision = AV_RB8(buf + 1); /* size of coefficients */
qtable_len = AV_RB16(buf + 2); /* length in bytes */
buf += 4;
len -= 4;
if (precision)
av_log(ctx, AV_LOG_WARNING, "Only 8-bit precision is supported.\n");
if (qtable_len > 0) {
if (len < qtable_len) {
av_log(ctx, AV_LOG_ERROR, "Too short RTP/JPEG packet.\n");
return AVERROR_INVALIDDATA;
}
qtables = buf;
buf += qtable_len;
len -= qtable_len;
if (q < 255) {
if (jpeg->qtables_len[q - 128] &&
(jpeg->qtables_len[q - 128] != qtable_len ||
memcmp(qtables, &jpeg->qtables[q - 128][0], qtable_len))) {
av_log(ctx, AV_LOG_WARNING,
"Quantization tables for q=%d changed\n", q);
} else if (!jpeg->qtables_len[q - 128] && qtable_len <= 128) {
memcpy(&jpeg->qtables[q - 128][0], qtables,
qtable_len);
jpeg->qtables_len[q - 128] = qtable_len;
}
}
} else {
if (q == 255) {
av_log(ctx, AV_LOG_ERROR,
"Invalid RTP/JPEG packet. Quantization tables not found.\n");
return AVERROR_INVALIDDATA;
}
if (!jpeg->qtables_len[q - 128]) {
av_log(ctx, AV_LOG_ERROR,
"No quantization tables known for q=%d yet.\n", q);
return AVERROR_INVALIDDATA;
}
qtables = &jpeg->qtables[q - 128][0];
qtable_len = jpeg->qtables_len[q - 128];
}
} else { /* q <= 127 */
if (q == 0 || q > 99) {
av_log(ctx, AV_LOG_ERROR, "Reserved q value %d\n", q);
return AVERROR_INVALIDDATA;
}
create_default_qtables(new_qtables, q);
qtables = new_qtables;
qtable_len = sizeof(new_qtables);
}
/* Skip the current frame in case of the end packet
* has been lost somewhere. */
ffio_free_dyn_buf(&jpeg->frame);
if ((ret = avio_open_dyn_buf(&jpeg->frame)) < 0)
return ret;
jpeg->timestamp = *timestamp;
/* Generate a frame and scan headers that can be prepended to the
* RTP/JPEG data payload to produce a JPEG compressed image in
* interchange format. */
jpeg->hdr_size = jpeg_create_header(hdr, sizeof(hdr), type, width,
height, qtables,
qtable_len / 64, dri);
/* Copy JPEG header to frame buffer. */
avio_write(jpeg->frame, hdr, jpeg->hdr_size);
}
if (!jpeg->frame) {
av_log(ctx, AV_LOG_ERROR,
"Received packet without a start chunk; dropping frame.\n");
return AVERROR(EAGAIN);
}
if (jpeg->timestamp != *timestamp) {
/* Skip the current frame if timestamp is incorrect.
* A start packet has been lost somewhere. */
ffio_free_dyn_buf(&jpeg->frame);
av_log(ctx, AV_LOG_ERROR, "RTP timestamps don't match.\n");
return AVERROR_INVALIDDATA;
}
if (off != avio_tell(jpeg->frame) - jpeg->hdr_size) {
av_log(ctx, AV_LOG_ERROR,
"Missing packets; dropping frame.\n");
return AVERROR(EAGAIN);
}
/* Copy data to frame buffer. */
avio_write(jpeg->frame, buf, len);
if (flags & RTP_FLAG_MARKER) {
/* End of JPEG data packet. */
uint8_t buf[2] = { 0xff, EOI };
/* Put EOI marker. */
avio_write(jpeg->frame, buf, sizeof(buf));
/* Prepare the JPEG packet. */
if ((ret = ff_rtp_finalize_packet(pkt, &jpeg->frame, st->index)) < 0) {
av_log(ctx, AV_LOG_ERROR,
"Error occurred when getting frame buffer.\n");
return ret;
}
return 0;
}
return AVERROR(EAGAIN);
}
const RTPDynamicProtocolHandler ff_jpeg_dynamic_handler = {
.enc_name = "JPEG",
.codec_type = AVMEDIA_TYPE_VIDEO,
.codec_id = AV_CODEC_ID_MJPEG,
.priv_data_size = sizeof(PayloadContext),
.close = jpeg_close_context,
.parse_packet = jpeg_parse_packet,
.static_payload_id = 26,
};
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