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/* |
* MPEG1 / MPEG2 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 "parser.h" |
#include "mpeg12.h" |
#include "internal.h" |
|
struct MpvParseContext { |
ParseContext pc; |
AVRational frame_rate; |
int progressive_sequence; |
int width, height; |
}; |
|
|
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 bit_rate = 0; |
int vbv_delay = 0; |
//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){ |
avcodec_set_dimensions(avctx, pc->width, pc->height); |
did_set_size=1; |
} |
frame_rate_index = buf[3] & 0xf; |
pc->frame_rate.den = avctx->time_base.den = ff_mpeg12_frame_rate_tab[frame_rate_index].num; |
pc->frame_rate.num = avctx->time_base.num = ff_mpeg12_frame_rate_tab[frame_rate_index].den; |
bit_rate = (buf[4]<<10) | (buf[5]<<2) | (buf[6]>>6); |
avctx->codec_id = AV_CODEC_ID_MPEG1VIDEO; |
} |
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); |
|
pc->width |=(horiz_size_ext << 12); |
pc->height |=( vert_size_ext << 12); |
bit_rate = (bit_rate&0x3FFFF) | (bit_rate_ext << 18); |
if(did_set_size) |
avcodec_set_dimensions(avctx, pc->width, pc->height); |
avctx->time_base.den = pc->frame_rate.den * (frame_rate_ext_n + 1) * 2; |
avctx->time_base.num = pc->frame_rate.num * (frame_rate_ext_d + 1); |
avctx->codec_id = AV_CODEC_ID_MPEG2VIDEO; |
} |
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) { |
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 (avctx->codec_id == AV_CODEC_ID_MPEG2VIDEO && bit_rate) { |
avctx->rc_max_rate = 400*bit_rate; |
} else if (avctx->codec_id == AV_CODEC_ID_MPEG1VIDEO && bit_rate && |
(bit_rate != 0x3FFFF || vbv_delay != 0xFFFF)) { |
avctx->bit_rate = 400*bit_rate; |
} |
} |
|
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= ff_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); |
av_dlog(NULL, "pict_type=%d frame_rate=%0.3f repeat_pict=%d\n", |
s->pict_type, (double)avctx->time_base.den / avctx->time_base.num, s->repeat_pict); |
|
*poutbuf = buf; |
*poutbuf_size = buf_size; |
return next; |
} |
|
static int mpegvideo_split(AVCodecContext *avctx, |
const uint8_t *buf, int buf_size) |
{ |
int i; |
uint32_t state= -1; |
int found=0; |
|
for(i=0; i<buf_size; i++){ |
state= (state<<8) | buf[i]; |
if(state == 0x1B3){ |
found=1; |
}else if(found && state != 0x1B5 && state < 0x200 && state >= 0x100) |
return i-3; |
} |
return 0; |
} |
|
static int mpegvideo_parse_init(AVCodecParserContext *s) |
{ |
s->pict_type = AV_PICTURE_TYPE_NONE; // first frame might be partial |
return 0; |
} |
|
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, |
.split = mpegvideo_split, |
}; |