static int jpeg_parse_packet(AVFormatContext *ctx, PayloadContext *jpeg, AVStream *st, AVPacket *pkt, uint32_t *timestamp, const uint8_t *buf, int len, uint16_t seq, int flags) { uint8_t type, q, width, height; const uint8_t *qtables = NULL; uint16_t qtable_len; uint32_t off; int ret; if (len < 8) { av_log(ctx, AV_LOG_ERROR, "Too short RTP/JPEG packet.\n"); return AVERROR_INVALIDDATA; } /* Parse the main JPEG header. */ off = AV_RB24(buf + 1); /* fragment byte offset */ type = AV_RB8(buf + 4); /* id of jpeg decoder params */ q = AV_RB8(buf + 5); /* quantization factor (or table id) */ width = AV_RB8(buf + 6); /* frame width in 8 pixel blocks */ height = AV_RB8(buf + 7); /* frame height in 8 pixel blocks */ buf += 8; len -= 8; /* Parse the restart marker header. */ if (type > 63) { av_log(ctx, AV_LOG_ERROR, "Unimplemented RTP/JPEG restart marker header.\n"); return AVERROR_PATCHWELCOME; } if (type > 1) { av_log(ctx, AV_LOG_ERROR, "Unimplemented RTP/JPEG type %d\n", type); return AVERROR_PATCHWELCOME; } /* Parse the quantization table header. */ if (off == 0) { /* Start of JPEG data packet. */ uint8_t new_qtables[128]; uint8_t hdr[1024]; if (q > 127) { uint8_t precision; if (len < 4) { av_log(ctx, AV_LOG_ERROR, "Too short RTP/JPEG packet.\n"); return AVERROR_INVALIDDATA; } /* The first byte is reserved for future use. */ precision = AV_RB8(buf + 1); /* size of coefficients */ qtable_len = AV_RB16(buf + 2); /* length in bytes */ buf += 4; len -= 4; if (precision) av_log(ctx, AV_LOG_WARNING, "Only 8-bit precision is supported.\n"); if (qtable_len > 0) { if (len < qtable_len) { av_log(ctx, AV_LOG_ERROR, "Too short RTP/JPEG packet.\n"); return AVERROR_INVALIDDATA; } qtables = buf; buf += qtable_len; len -= qtable_len; if (q < 255) { if (jpeg->qtables_len[q - 128] && (jpeg->qtables_len[q - 128] != qtable_len || memcmp(qtables, &jpeg->qtables[q - 128][0], qtable_len))) { av_log(ctx, AV_LOG_WARNING, "Quantization tables for q=%d changed\n", q); } else if (!jpeg->qtables_len[q - 128] && qtable_len <= 128) { memcpy(&jpeg->qtables[q - 128][0], qtables, qtable_len); jpeg->qtables_len[q - 128] = qtable_len; } } } else { if (q == 255) { av_log(ctx, AV_LOG_ERROR, "Invalid RTP/JPEG packet. Quantization tables not found.\n"); return AVERROR_INVALIDDATA; } if (!jpeg->qtables_len[q - 128]) { av_log(ctx, AV_LOG_ERROR, "No quantization tables known for q=%d yet.\n", q); return AVERROR_INVALIDDATA; } qtables = &jpeg->qtables[q - 128][0]; qtable_len = jpeg->qtables_len[q - 128]; } } else { /* q <= 127 */ if (q == 0 || q > 99) { av_log(ctx, AV_LOG_ERROR, "Reserved q value %d\n", q); return AVERROR_INVALIDDATA; } create_default_qtables(new_qtables, q); qtables = new_qtables; qtable_len = sizeof(new_qtables); } /* Skip the current frame in case of the end packet * has been lost somewhere. */ ffio_free_dyn_buf(&jpeg->frame); if ((ret = avio_open_dyn_buf(&jpeg->frame)) < 0) return ret; jpeg->timestamp = *timestamp; /* Generate a frame and scan headers that can be prepended to the * RTP/JPEG data payload to produce a JPEG compressed image in * interchange format. */ jpeg->hdr_size = jpeg_create_header(hdr, sizeof(hdr), type, width, height, qtables, qtable_len / 64); /* Copy JPEG header to frame buffer. */ avio_write(jpeg->frame, hdr, jpeg->hdr_size); } if (!jpeg->frame) { av_log(ctx, AV_LOG_ERROR, "Received packet without a start chunk; dropping frame.\n"); return AVERROR(EAGAIN); } if (jpeg->timestamp != *timestamp) { /* Skip the current frame if timestamp is incorrect. * A start packet has been lost somewhere. */ ffio_free_dyn_buf(&jpeg->frame); av_log(ctx, AV_LOG_ERROR, "RTP timestamps don't match.\n"); return AVERROR_INVALIDDATA; } if (off != avio_tell(jpeg->frame) - jpeg->hdr_size) { av_log(ctx, AV_LOG_ERROR, "Missing packets; dropping frame.\n"); return AVERROR(EAGAIN); } /* Copy data to frame buffer. */ avio_write(jpeg->frame, buf, len); if (flags & RTP_FLAG_MARKER) { /* End of JPEG data packet. */ uint8_t buf[2] = { 0xff, EOI }; /* Put EOI marker. */ avio_write(jpeg->frame, buf, sizeof(buf)); /* Prepare the JPEG packet. */ if ((ret = ff_rtp_finalize_packet(pkt, &jpeg->frame, st->index)) < 0) { av_log(ctx, AV_LOG_ERROR, "Error occurred when getting frame buffer.\n"); return ret; } return 0; } return AVERROR(EAGAIN); }