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https://git.videolan.org/git/ffmpeg.git
synced 2024-08-18 07:15:04 +02:00
cleanup mpeg1/2 bitstream parser
Originally committed as revision 1813 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
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5cd62665f0
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80097bbf71
@ -325,14 +325,16 @@ static int mpeg4_find_frame_end(MpegEncContext *s, uint8_t *buf, int buf_size){
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}
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}
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}
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for(; i<buf_size; i++){
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if(vop_found){
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for(; i<buf_size; i++){
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state= (state<<8) | buf[i];
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if((state&0xFFFFFF00) == 0x100){
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pc->frame_start_found=0;
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pc->state=-1;
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return i-3;
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}
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}
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}
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pc->frame_start_found= vop_found;
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pc->state= state;
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@ -1543,16 +1543,8 @@ static inline int mpeg2_decode_block_intra(MpegEncContext *s,
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return 0;
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}
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/* compressed picture size */
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#define PICTURE_BUFFER_SIZE 100000
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typedef struct Mpeg1Context {
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MpegEncContext mpeg_enc_ctx;
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uint32_t header_state;
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int start_code; /* current start code */
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uint8_t buffer[PICTURE_BUFFER_SIZE];
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uint8_t *buf_ptr;
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int buffer_size;
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int mpeg_enc_ctx_allocated; /* true if decoding context allocated */
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int repeat_field; /* true if we must repeat the field */
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} Mpeg1Context;
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@ -1565,11 +1557,7 @@ static int mpeg_decode_init(AVCodecContext *avctx)
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common_init(&s->mpeg_enc_ctx);
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init_vlcs(&s->mpeg_enc_ctx);
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s->header_state = 0xff;
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s->mpeg_enc_ctx_allocated = 0;
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s->buffer_size = PICTURE_BUFFER_SIZE;
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s->start_code = -1;
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s->buf_ptr = s->buffer;
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s->mpeg_enc_ctx.picture_number = 0;
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s->repeat_field = 0;
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s->mpeg_enc_ctx.codec_id= avctx->codec->id;
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@ -1578,14 +1566,12 @@ static int mpeg_decode_init(AVCodecContext *avctx)
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/* return the 8 bit start code value and update the search
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state. Return -1 if no start code found */
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static int find_start_code(uint8_t **pbuf_ptr, uint8_t *buf_end,
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uint32_t *header_state)
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static int find_start_code(uint8_t **pbuf_ptr, uint8_t *buf_end)
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{
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uint8_t *buf_ptr;
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unsigned int state, v;
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unsigned int state=0xFFFFFFFF, v;
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int val;
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state = *header_state;
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buf_ptr = *pbuf_ptr;
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while (buf_ptr < buf_end) {
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v = *buf_ptr++;
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@ -1599,7 +1585,6 @@ static int find_start_code(uint8_t **pbuf_ptr, uint8_t *buf_end,
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val = -1;
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found:
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*pbuf_ptr = buf_ptr;
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*header_state = state;
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return val;
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}
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@ -1809,7 +1794,7 @@ static void mpeg_decode_extension(AVCodecContext *avctx,
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static int mpeg_decode_slice(AVCodecContext *avctx,
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AVFrame *pict,
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int start_code,
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uint8_t *buf, int buf_size)
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uint8_t **buf, int buf_size)
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{
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Mpeg1Context *s1 = avctx->priv_data;
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MpegEncContext *s = &s1->mpeg_enc_ctx;
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@ -1874,7 +1859,7 @@ static int mpeg_decode_slice(AVCodecContext *avctx,
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}
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s->first_slice = 0;
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init_get_bits(&s->gb, buf, buf_size*8);
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init_get_bits(&s->gb, *buf, buf_size*8);
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s->qscale = get_qscale(s);
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if(s->qscale == 0){
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@ -1928,7 +1913,6 @@ static int mpeg_decode_slice(AVCodecContext *avctx,
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motion_x = s->mv[0][0][0];
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motion_y = s->mv[0][0][1];
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} else /*if (s->mv_type == MV_TYPE_FIELD)*/ {
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int i;
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motion_x = s->mv[0][0][0] + s->mv[0][1][0];
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motion_y = s->mv[0][0][1] + s->mv[0][1][1];
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motion_x = (motion_x>>1) | (motion_x&1);
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@ -1996,6 +1980,8 @@ eos: //end of slice
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emms_c();
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*buf += get_bits_count(&s->gb)/8 - 1;
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//intf("%d %d %d %d\n", s->mb_y, s->mb_height, s->pict_type, s->picture_number);
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/* end of slice reached */
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if (s->mb_y<<field_pic == s->mb_height && !s->first_field) {
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@ -2017,9 +2003,7 @@ eos: //end of slice
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s->picture_number++;
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/* latency of 1 frame for I and P frames */
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/* XXX: use another variable than picture_number */
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if (s->last_picture_ptr == NULL) {
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return DECODE_SLICE_OK;
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} else {
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if (s->last_picture_ptr != NULL) {
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*pict= *(AVFrame*)&s->last_picture;
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ff_print_debug_info(s, s->last_picture_ptr);
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}
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@ -2170,17 +2154,55 @@ static void mpeg_decode_user_data(AVCodecContext *avctx,
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}
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}
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/**
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* finds the end of the current frame in the bitstream.
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* @return the position of the first byte of the next frame, or -1
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*/
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static int mpeg1_find_frame_end(MpegEncContext *s, uint8_t *buf, int buf_size){
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ParseContext *pc= &s->parse_context;
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int i;
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uint32_t state;
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state= pc->state;
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i=0;
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if(!pc->frame_start_found){
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for(i=0; i<buf_size; i++){
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state= (state<<8) | buf[i];
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if(state >= SLICE_MIN_START_CODE && state <= SLICE_MAX_START_CODE){
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i++;
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pc->frame_start_found=1;
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break;
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}
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}
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}
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if(pc->frame_start_found){
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for(; i<buf_size; i++){
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state= (state<<8) | buf[i];
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if((state&0xFFFFFF00) == 0x100){
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if(state < SLICE_MIN_START_CODE || state > SLICE_MAX_START_CODE){
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pc->frame_start_found=0;
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pc->state=-1;
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return i-3;
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}
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}
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}
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}
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pc->state= state;
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return -1;
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}
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/* handle buffering and image synchronisation */
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static int mpeg_decode_frame(AVCodecContext *avctx,
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void *data, int *data_size,
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uint8_t *buf, int buf_size)
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{
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Mpeg1Context *s = avctx->priv_data;
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uint8_t *buf_end, *buf_ptr, *buf_start;
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int len, start_code_found, ret, code, start_code, input_size;
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uint8_t *buf_end, *buf_ptr;
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int ret, start_code, input_size;
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AVFrame *picture = data;
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MpegEncContext *s2 = &s->mpeg_enc_ctx;
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dprintf("fill_buffer\n");
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*data_size = 0;
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@ -2195,6 +2217,15 @@ static int mpeg_decode_frame(AVCodecContext *avctx,
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return 0;
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}
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if(s2->flags&CODEC_FLAG_TRUNCATED){
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int next;
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next= mpeg1_find_frame_end(s2, buf, buf_size);
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if( ff_combine_frame(s2, next, &buf, &buf_size) < 0 )
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return buf_size;
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}
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buf_ptr = buf;
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buf_end = buf + buf_size;
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@ -2209,60 +2240,34 @@ static int mpeg_decode_frame(AVCodecContext *avctx,
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}
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}
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#endif
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while (buf_ptr < buf_end) {
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buf_start = buf_ptr;
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for(;;) {
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/* find start next code */
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code = find_start_code(&buf_ptr, buf_end, &s->header_state);
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if (code >= 0) {
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start_code_found = 1;
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} else {
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start_code_found = 0;
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start_code = find_start_code(&buf_ptr, buf_end);
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if (start_code < 0){
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printf("missing end of picture\n");
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return FFMAX(1, buf_ptr - buf - s2->parse_context.last_index);
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}
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/* copy to buffer */
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len = buf_ptr - buf_start;
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if (len + (s->buf_ptr - s->buffer) > s->buffer_size) {
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/* data too big : flush */
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s->buf_ptr = s->buffer;
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if (start_code_found)
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s->start_code = code;
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} else {
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memcpy(s->buf_ptr, buf_start, len);
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s->buf_ptr += len;
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if( (!(s2->flags&CODEC_FLAG_TRUNCATED)) && (!start_code_found)
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&& s->buf_ptr+4<s->buffer+s->buffer_size){
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start_code_found= 1;
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code= 0x1FF;
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s->header_state=0xFF;
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s->buf_ptr[0]=0;
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s->buf_ptr[1]=0;
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s->buf_ptr[2]=1;
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s->buf_ptr[3]=0xFF;
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s->buf_ptr+=4;
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}
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if (start_code_found) {
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/* prepare data for next start code */
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input_size = s->buf_ptr - s->buffer;
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start_code = s->start_code;
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s->buf_ptr = s->buffer;
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s->start_code = code;
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input_size = buf_end - buf_ptr;
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switch(start_code) {
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case SEQ_START_CODE:
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mpeg1_decode_sequence(avctx, s->buffer,
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mpeg1_decode_sequence(avctx, buf_ptr,
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input_size);
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break;
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case PICTURE_START_CODE:
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/* we have a complete image : we try to decompress it */
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mpeg1_decode_picture(avctx,
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s->buffer, input_size);
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buf_ptr, input_size);
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break;
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case EXT_START_CODE:
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mpeg_decode_extension(avctx,
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s->buffer, input_size);
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buf_ptr, input_size);
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break;
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case USER_START_CODE:
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mpeg_decode_user_data(avctx,
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s->buffer, input_size);
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buf_ptr, input_size);
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break;
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default:
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if (start_code >= SLICE_MIN_START_CODE &&
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@ -2274,15 +2279,16 @@ static int mpeg_decode_frame(AVCodecContext *avctx,
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if(avctx->hurry_up && s2->pict_type==B_TYPE) break;
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/* skip everything if we are in a hurry>=5 */
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if(avctx->hurry_up>=5) break;
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if (!s->mpeg_enc_ctx_allocated) break;
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ret = mpeg_decode_slice(avctx, picture,
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start_code, s->buffer, input_size);
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start_code, &buf_ptr, input_size);
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if (ret == DECODE_SLICE_EOP) {
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*data_size = sizeof(AVPicture);
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goto the_end;
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if(s2->last_picture_ptr) //FIXME merge with the stuff in mpeg_decode_slice
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*data_size = sizeof(AVPicture);
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return FFMAX(1, buf_ptr - buf - s2->parse_context.last_index);
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}else if(ret < 0){
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if(ret == DECODE_SLICE_ERROR)
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ff_er_add_slice(s2, s2->resync_mb_x, s2->resync_mb_y, s2->mb_x, s2->mb_y, AC_ERROR|DC_ERROR|MV_ERROR);
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@ -2293,11 +2299,7 @@ static int mpeg_decode_frame(AVCodecContext *avctx,
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}
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break;
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}
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}
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}
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}
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the_end:
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return buf_ptr - buf;
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}
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static int mpeg_decode_end(AVCodecContext *avctx)
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