static int mpegaudio_parse(AVCodecParserContext *s1, AVCodecContext *avctx, uint8_t **poutbuf, int *poutbuf_size, const uint8_t *buf, int buf_size) { MpegAudioParseContext *s = s1->priv_data; int len, ret; uint32_t header; const uint8_t *buf_ptr; *poutbuf = NULL; *poutbuf_size = 0; buf_ptr = buf; while (buf_size > 0) { len = s->inbuf_ptr - s->inbuf; if (s->frame_size == 0) { /* special case for next header for first frame in free format case (XXX: find a simpler method) */ if (s->free_format_next_header != 0) { s->inbuf[0] = s->free_format_next_header >> 24; s->inbuf[1] = s->free_format_next_header >> 16; s->inbuf[2] = s->free_format_next_header >> 8; s->inbuf[3] = s->free_format_next_header; s->inbuf_ptr = s->inbuf + 4; s->free_format_next_header = 0; goto got_header; } /* no header seen : find one. We need at least MPA_HEADER_SIZE bytes to parse it */ len = MPA_HEADER_SIZE - len; if (len > buf_size) len = buf_size; if (len > 0) { memcpy(s->inbuf_ptr, buf_ptr, len); buf_ptr += len; buf_size -= len; s->inbuf_ptr += len; } if ((s->inbuf_ptr - s->inbuf) >= MPA_HEADER_SIZE) { got_header: header = (s->inbuf[0] << 24) | (s->inbuf[1] << 16) | (s->inbuf[2] << 8) | s->inbuf[3]; ret = mpa_decode_header(avctx, header); if (ret < 0) { /* no sync found : move by one byte (inefficient, but simple!) */ memmove(s->inbuf, s->inbuf + 1, s->inbuf_ptr - s->inbuf - 1); s->inbuf_ptr--; dprintf("skip %x\n", header); /* reset free format frame size to give a chance to get a new bitrate */ s->free_format_frame_size = 0; } else { s->frame_size = ret; #if 0 /* free format: prepare to compute frame size */ if (decode_header(s, header) == 1) { s->frame_size = -1; } #endif } } } else #if 0 if (s->frame_size == -1) { /* free format : find next sync to compute frame size */ len = MPA_MAX_CODED_FRAME_SIZE - len; if (len > buf_size) len = buf_size; if (len == 0) { /* frame too long: resync */ s->frame_size = 0; memmove(s->inbuf, s->inbuf + 1, s->inbuf_ptr - s->inbuf - 1); s->inbuf_ptr--; } else { uint8_t *p, *pend; uint32_t header1; int padding; memcpy(s->inbuf_ptr, buf_ptr, len); /* check for header */ p = s->inbuf_ptr - 3; pend = s->inbuf_ptr + len - 4; while (p <= pend) { header = (p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3]; header1 = (s->inbuf[0] << 24) | (s->inbuf[1] << 16) | (s->inbuf[2] << 8) | s->inbuf[3]; /* check with high probability that we have a valid header */ if ((header & SAME_HEADER_MASK) == (header1 & SAME_HEADER_MASK)) { /* header found: update pointers */ len = (p + 4) - s->inbuf_ptr; buf_ptr += len; buf_size -= len; s->inbuf_ptr = p; /* compute frame size */ s->free_format_next_header = header; s->free_format_frame_size = s->inbuf_ptr - s->inbuf; padding = (header1 >> 9) & 1; if (s->layer == 1) s->free_format_frame_size -= padding * 4; else s->free_format_frame_size -= padding; dprintf("free frame size=%d padding=%d\n", s->free_format_frame_size, padding); decode_header(s, header1); goto next_data; } p++; } /* not found: simply increase pointers */ buf_ptr += len; s->inbuf_ptr += len; buf_size -= len; } } else #endif if (len < s->frame_size) { if (s->frame_size > MPA_MAX_CODED_FRAME_SIZE) s->frame_size = MPA_MAX_CODED_FRAME_SIZE; len = s->frame_size - len; if (len > buf_size) len = buf_size; memcpy(s->inbuf_ptr, buf_ptr, len); buf_ptr += len; s->inbuf_ptr += len; buf_size -= len; } // next_data: if (s->frame_size > 0 && (s->inbuf_ptr - s->inbuf) >= s->frame_size) { *poutbuf = s->inbuf; *poutbuf_size = s->inbuf_ptr - s->inbuf; s->inbuf_ptr = s->inbuf; s->frame_size = 0; break; } } return buf_ptr - buf; }