mirror of https://github.com/FFmpeg/FFmpeg.git
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
290 lines
11 KiB
290 lines
11 KiB
/* |
|
* MPEG-1 / MPEG-2 video parser |
|
* Copyright (c) 2000,2001 Fabrice Bellard |
|
* Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at> |
|
* |
|
* 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 "libavutil/avassert.h" |
|
#include "decode.h" |
|
#include "parser.h" |
|
#include "mpeg12.h" |
|
#include "mpeg12data.h" |
|
#include "startcode.h" |
|
|
|
struct MpvParseContext { |
|
ParseContext pc; |
|
AVRational frame_rate; |
|
int progressive_sequence; |
|
int width, height; |
|
}; |
|
|
|
/** |
|
* Find the end of the current frame in the bitstream. |
|
* @return the position of the first byte of the next frame, or -1 |
|
*/ |
|
static int mpeg1_find_frame_end(ParseContext *pc, const uint8_t *buf, |
|
int buf_size, AVCodecParserContext *s) |
|
{ |
|
int i; |
|
uint32_t state = pc->state; |
|
|
|
/* EOF considered as end of frame */ |
|
if (buf_size == 0) |
|
return 0; |
|
|
|
/* |
|
0 frame start -> 1/4 |
|
1 first_SEQEXT -> 0/2 |
|
2 first field start -> 3/0 |
|
3 second_SEQEXT -> 2/0 |
|
4 searching end |
|
*/ |
|
|
|
for (i = 0; i < buf_size; i++) { |
|
av_assert1(pc->frame_start_found >= 0 && pc->frame_start_found <= 4); |
|
if (pc->frame_start_found & 1) { |
|
if (state == EXT_START_CODE && (buf[i] & 0xF0) != 0x80) |
|
pc->frame_start_found--; |
|
else if (state == EXT_START_CODE + 2) { |
|
if ((buf[i] & 3) == 3) |
|
pc->frame_start_found = 0; |
|
else |
|
pc->frame_start_found = (pc->frame_start_found + 1) & 3; |
|
} |
|
state++; |
|
} else { |
|
i = avpriv_find_start_code(buf + i, buf + buf_size, &state) - buf - 1; |
|
if (pc->frame_start_found == 0 && state >= SLICE_MIN_START_CODE && state <= SLICE_MAX_START_CODE) { |
|
i++; |
|
pc->frame_start_found = 4; |
|
} |
|
if (state == SEQ_END_CODE) { |
|
pc->frame_start_found = 0; |
|
pc->state = -1; |
|
return i + 1; |
|
} |
|
if (pc->frame_start_found == 2 && state == SEQ_START_CODE) |
|
pc->frame_start_found = 0; |
|
if (pc->frame_start_found < 4 && state == EXT_START_CODE) |
|
pc->frame_start_found++; |
|
if (pc->frame_start_found == 4 && (state & 0xFFFFFF00) == 0x100) { |
|
if (state < SLICE_MIN_START_CODE || state > SLICE_MAX_START_CODE) { |
|
pc->frame_start_found = 0; |
|
pc->state = -1; |
|
return i - 3; |
|
} |
|
} |
|
if (pc->frame_start_found == 0 && s && state == PICTURE_START_CODE) { |
|
ff_fetch_timestamp(s, i - 3, 1, i > 3); |
|
} |
|
} |
|
} |
|
pc->state = state; |
|
return END_NOT_FOUND; |
|
} |
|
|
|
static void mpegvideo_extract_headers(AVCodecParserContext *s, |
|
AVCodecContext *avctx, |
|
const uint8_t *buf, int buf_size) |
|
{ |
|
struct MpvParseContext *pc = s->priv_data; |
|
const uint8_t *buf_end = buf + buf_size; |
|
uint32_t start_code; |
|
int frame_rate_index, ext_type, bytes_left; |
|
int frame_rate_ext_n, frame_rate_ext_d; |
|
int top_field_first, repeat_first_field, progressive_frame; |
|
int horiz_size_ext, vert_size_ext, bit_rate_ext; |
|
int did_set_size=0; |
|
int set_dim_ret = 0; |
|
int bit_rate = 0; |
|
int vbv_delay = 0; |
|
int chroma_format; |
|
enum AVPixelFormat pix_fmt = AV_PIX_FMT_NONE; |
|
//FIXME replace the crap with get_bits() |
|
s->repeat_pict = 0; |
|
|
|
while (buf < buf_end) { |
|
start_code= -1; |
|
buf= avpriv_find_start_code(buf, buf_end, &start_code); |
|
bytes_left = buf_end - buf; |
|
switch(start_code) { |
|
case PICTURE_START_CODE: |
|
if (bytes_left >= 2) { |
|
s->pict_type = (buf[1] >> 3) & 7; |
|
if (bytes_left >= 4) |
|
vbv_delay = ((buf[1] & 0x07) << 13) | (buf[2] << 5) | (buf[3] >> 3); |
|
} |
|
break; |
|
case SEQ_START_CODE: |
|
if (bytes_left >= 7) { |
|
pc->width = (buf[0] << 4) | (buf[1] >> 4); |
|
pc->height = ((buf[1] & 0x0f) << 8) | buf[2]; |
|
if(!avctx->width || !avctx->height || !avctx->coded_width || !avctx->coded_height){ |
|
set_dim_ret = ff_set_dimensions(avctx, pc->width, pc->height); |
|
did_set_size=1; |
|
} |
|
pix_fmt = AV_PIX_FMT_YUV420P; |
|
frame_rate_index = buf[3] & 0xf; |
|
pc->frame_rate = avctx->framerate = ff_mpeg12_frame_rate_tab[frame_rate_index]; |
|
bit_rate = (buf[4]<<10) | (buf[5]<<2) | (buf[6]>>6); |
|
avctx->codec_id = AV_CODEC_ID_MPEG1VIDEO; |
|
avctx->ticks_per_frame = 1; |
|
} |
|
break; |
|
case EXT_START_CODE: |
|
if (bytes_left >= 1) { |
|
ext_type = (buf[0] >> 4); |
|
switch(ext_type) { |
|
case 0x1: /* sequence extension */ |
|
if (bytes_left >= 6) { |
|
horiz_size_ext = ((buf[1] & 1) << 1) | (buf[2] >> 7); |
|
vert_size_ext = (buf[2] >> 5) & 3; |
|
bit_rate_ext = ((buf[2] & 0x1F)<<7) | (buf[3]>>1); |
|
frame_rate_ext_n = (buf[5] >> 5) & 3; |
|
frame_rate_ext_d = (buf[5] & 0x1f); |
|
pc->progressive_sequence = buf[1] & (1 << 3); |
|
avctx->has_b_frames= !(buf[5] >> 7); |
|
|
|
chroma_format = (buf[1] >> 1) & 3; |
|
switch (chroma_format) { |
|
case 1: pix_fmt = AV_PIX_FMT_YUV420P; break; |
|
case 2: pix_fmt = AV_PIX_FMT_YUV422P; break; |
|
case 3: pix_fmt = AV_PIX_FMT_YUV444P; break; |
|
} |
|
|
|
pc->width = (pc->width & 0xFFF) | (horiz_size_ext << 12); |
|
pc->height = (pc->height& 0xFFF) | ( vert_size_ext << 12); |
|
bit_rate = (bit_rate&0x3FFFF) | (bit_rate_ext << 18); |
|
if(did_set_size) |
|
set_dim_ret = ff_set_dimensions(avctx, pc->width, pc->height); |
|
avctx->framerate.num = pc->frame_rate.num * (frame_rate_ext_n + 1); |
|
avctx->framerate.den = pc->frame_rate.den * (frame_rate_ext_d + 1); |
|
avctx->codec_id = AV_CODEC_ID_MPEG2VIDEO; |
|
avctx->ticks_per_frame = 2; |
|
} |
|
break; |
|
case 0x8: /* picture coding extension */ |
|
if (bytes_left >= 5) { |
|
top_field_first = buf[3] & (1 << 7); |
|
repeat_first_field = buf[3] & (1 << 1); |
|
progressive_frame = buf[4] & (1 << 7); |
|
|
|
/* check if we must repeat the frame */ |
|
s->repeat_pict = 1; |
|
if (repeat_first_field) { |
|
if (pc->progressive_sequence) { |
|
if (top_field_first) |
|
s->repeat_pict = 5; |
|
else |
|
s->repeat_pict = 3; |
|
} else if (progressive_frame) { |
|
s->repeat_pict = 2; |
|
} |
|
} |
|
|
|
if (!pc->progressive_sequence && !progressive_frame) { |
|
if (top_field_first) |
|
s->field_order = AV_FIELD_TT; |
|
else |
|
s->field_order = AV_FIELD_BB; |
|
} else |
|
s->field_order = AV_FIELD_PROGRESSIVE; |
|
} |
|
break; |
|
} |
|
} |
|
break; |
|
case -1: |
|
goto the_end; |
|
default: |
|
/* we stop parsing when we encounter a slice. It ensures |
|
that this function takes a negligible amount of time */ |
|
if (start_code >= SLICE_MIN_START_CODE && |
|
start_code <= SLICE_MAX_START_CODE) |
|
goto the_end; |
|
break; |
|
} |
|
} |
|
the_end: |
|
if (set_dim_ret < 0) |
|
av_log(avctx, AV_LOG_ERROR, "Failed to set dimensions\n"); |
|
|
|
if (avctx->codec_id == AV_CODEC_ID_MPEG2VIDEO && bit_rate) { |
|
avctx->rc_max_rate = 400LL*bit_rate; |
|
} |
|
if (bit_rate && |
|
((avctx->codec_id == AV_CODEC_ID_MPEG1VIDEO && bit_rate != 0x3FFFF) || vbv_delay != 0xFFFF)) { |
|
avctx->bit_rate = 400LL*bit_rate; |
|
} |
|
|
|
if (pix_fmt != AV_PIX_FMT_NONE) { |
|
s->format = pix_fmt; |
|
s->width = pc->width; |
|
s->height = pc->height; |
|
s->coded_width = FFALIGN(pc->width, 16); |
|
s->coded_height = FFALIGN(pc->height, 16); |
|
} |
|
} |
|
|
|
static int mpegvideo_parse(AVCodecParserContext *s, |
|
AVCodecContext *avctx, |
|
const uint8_t **poutbuf, int *poutbuf_size, |
|
const uint8_t *buf, int buf_size) |
|
{ |
|
struct MpvParseContext *pc1 = s->priv_data; |
|
ParseContext *pc= &pc1->pc; |
|
int next; |
|
|
|
if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){ |
|
next= buf_size; |
|
}else{ |
|
next = mpeg1_find_frame_end(pc, buf, buf_size, s); |
|
|
|
if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) { |
|
*poutbuf = NULL; |
|
*poutbuf_size = 0; |
|
return buf_size; |
|
} |
|
|
|
} |
|
/* we have a full frame : we just parse the first few MPEG headers |
|
to have the full timing information. The time take by this |
|
function should be negligible for uncorrupted streams */ |
|
mpegvideo_extract_headers(s, avctx, buf, buf_size); |
|
ff_dlog(NULL, "pict_type=%d frame_rate=%0.3f repeat_pict=%d\n", |
|
s->pict_type, av_q2d(avctx->framerate), s->repeat_pict); |
|
|
|
*poutbuf = buf; |
|
*poutbuf_size = buf_size; |
|
return next; |
|
} |
|
|
|
static int mpegvideo_parse_init(AVCodecParserContext *s) |
|
{ |
|
s->pict_type = AV_PICTURE_TYPE_NONE; // first frame might be partial |
|
return 0; |
|
} |
|
|
|
const AVCodecParser ff_mpegvideo_parser = { |
|
.codec_ids = { AV_CODEC_ID_MPEG1VIDEO, AV_CODEC_ID_MPEG2VIDEO }, |
|
.priv_data_size = sizeof(struct MpvParseContext), |
|
.parser_init = mpegvideo_parse_init, |
|
.parser_parse = mpegvideo_parse, |
|
.parser_close = ff_parse_close, |
|
};
|
|
|