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ffmpeg/libavformat/rtpenc_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 Packetizer, 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 "libavcodec/bytestream.h"
#include "libavcodec/mjpeg.h"
#include "libavcodec/jpegtables.h"
#include "libavutil/intreadwrite.h"
#include "rtpenc.h"
void ff_rtp_send_jpeg(AVFormatContext *s1, const uint8_t *buf, int size)
{
RTPMuxContext *s = s1->priv_data;
const uint8_t *qtables[4] = { NULL };
int nb_qtables = 0;
uint8_t type;
uint8_t w, h;
uint8_t *p;
int off = 0; /* fragment offset of the current JPEG frame */
int len;
int i;
int default_huffman_tables = 0;
s->buf_ptr = s->buf;
s->timestamp = s->cur_timestamp;
/* convert video pixel dimensions from pixels to blocks */
w = AV_CEIL_RSHIFT(s1->streams[0]->codecpar->width, 3);
h = AV_CEIL_RSHIFT(s1->streams[0]->codecpar->height, 3);
/* get the pixel format type or fail */
if (s1->streams[0]->codecpar->format == AV_PIX_FMT_YUVJ422P ||
(s1->streams[0]->codecpar->color_range == AVCOL_RANGE_JPEG &&
s1->streams[0]->codecpar->format == AV_PIX_FMT_YUV422P)) {
type = 0;
} else if (s1->streams[0]->codecpar->format == AV_PIX_FMT_YUVJ420P ||
(s1->streams[0]->codecpar->color_range == AVCOL_RANGE_JPEG &&
s1->streams[0]->codecpar->format == AV_PIX_FMT_YUV420P)) {
type = 1;
} else {
av_log(s1, AV_LOG_ERROR, "Unsupported pixel format\n");
return;
}
/* preparse the header for getting some info */
for (i = 0; i < size; i++) {
if (buf[i] != 0xff)
continue;
if (buf[i + 1] == DQT) {
int tables, j;
if (buf[i + 4] & 0xF0)
av_log(s1, AV_LOG_WARNING,
"Only 8-bit precision is supported.\n");
/* a quantization table is 64 bytes long */
tables = AV_RB16(&buf[i + 2]) / 65;
if (i + 5 + tables * 65 > size) {
av_log(s1, AV_LOG_ERROR, "Too short JPEG header. Aborted!\n");
return;
}
if (nb_qtables + tables > 4) {
av_log(s1, AV_LOG_ERROR, "Invalid number of quantisation tables\n");
return;
}
for (j = 0; j < tables; j++)
qtables[nb_qtables + j] = buf + i + 5 + j * 65;
nb_qtables += tables;
} else if (buf[i + 1] == SOF0) {
if (buf[i + 14] != 17 || buf[i + 17] != 17) {
av_log(s1, AV_LOG_ERROR,
"Only 1x1 chroma blocks are supported. Aborted!\n");
return;
}
} else if (buf[i + 1] == DHT) {
int dht_size = AV_RB16(&buf[i + 2]);
default_huffman_tables |= 1 << 4;
i += 3;
dht_size -= 2;
if (i + dht_size >= size)
continue;
while (dht_size > 0)
switch (buf[i + 1]) {
case 0x00:
if ( dht_size >= 29
&& !memcmp(buf + i + 2, ff_mjpeg_bits_dc_luminance + 1, 16)
&& !memcmp(buf + i + 18, ff_mjpeg_val_dc, 12)) {
default_huffman_tables |= 1;
i += 29;
dht_size -= 29;
} else {
i += dht_size;
dht_size = 0;
}
break;
case 0x01:
if ( dht_size >= 29
&& !memcmp(buf + i + 2, ff_mjpeg_bits_dc_chrominance + 1, 16)
&& !memcmp(buf + i + 18, ff_mjpeg_val_dc, 12)) {
default_huffman_tables |= 1 << 1;
i += 29;
dht_size -= 29;
} else {
i += dht_size;
dht_size = 0;
}
break;
case 0x10:
if ( dht_size >= 179
&& !memcmp(buf + i + 2, ff_mjpeg_bits_ac_luminance + 1, 16)
&& !memcmp(buf + i + 18, ff_mjpeg_val_ac_luminance, 162)) {
default_huffman_tables |= 1 << 2;
i += 179;
dht_size -= 179;
} else {
i += dht_size;
dht_size = 0;
}
break;
case 0x11:
if ( dht_size >= 179
&& !memcmp(buf + i + 2, ff_mjpeg_bits_ac_chrominance + 1, 16)
&& !memcmp(buf + i + 18, ff_mjpeg_val_ac_chrominance, 162)) {
default_huffman_tables |= 1 << 3;
i += 179;
dht_size -= 179;
} else {
i += dht_size;
dht_size = 0;
}
break;
default:
i += dht_size;
dht_size = 0;
continue;
}
} else if (buf[i + 1] == SOS) {
/* SOS is last marker in the header */
i += AV_RB16(&buf[i + 2]) + 2;
if (i > size) {
av_log(s1, AV_LOG_ERROR,
"Insufficient data. Aborted!\n");
return;
}
break;
}
}
if (default_huffman_tables && default_huffman_tables != 31) {
av_log(s1, AV_LOG_ERROR,
"RFC 2435 requires standard Huffman tables for jpeg\n");
return;
}
if (nb_qtables && nb_qtables != 2)
av_log(s1, AV_LOG_WARNING,
"RFC 2435 suggests two quantization tables, %d provided\n",
nb_qtables);
/* skip JPEG header */
buf += i;
size -= i;
for (i = size - 2; i >= 0; i--) {
if (buf[i] == 0xff && buf[i + 1] == EOI) {
/* Remove the EOI marker */
size = i;
break;
}
}
p = s->buf_ptr;
while (size > 0) {
int hdr_size = 8;
if (off == 0 && nb_qtables)
hdr_size += 4 + 64 * nb_qtables;
/* payload max in one packet */
len = FFMIN(size, s->max_payload_size - hdr_size);
/* set main header */
bytestream_put_byte(&p, 0);
bytestream_put_be24(&p, off);
bytestream_put_byte(&p, type);
bytestream_put_byte(&p, 255);
bytestream_put_byte(&p, w);
bytestream_put_byte(&p, h);
if (off == 0 && nb_qtables) {
/* set quantization tables header */
bytestream_put_byte(&p, 0);
bytestream_put_byte(&p, 0);
bytestream_put_be16(&p, 64 * nb_qtables);
for (i = 0; i < nb_qtables; i++)
bytestream_put_buffer(&p, qtables[i], 64);
}
/* copy payload data */
memcpy(p, buf, len);
/* marker bit is last packet in frame */
ff_rtp_send_data(s1, s->buf, len + hdr_size, size == len);
buf += len;
size -= len;
off += len;
p = s->buf;
}
}
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