static int yuv4_read_header(AVFormatContext *s) { char header[MAX_YUV4_HEADER + 10]; // Include headroom for // the longest option char *tokstart, *tokend, *header_end; int i; AVIOContext *pb = s->pb; int width = -1, height = -1, raten = 0, rated = 0, aspectn = 0, aspectd = 0; enum AVPixelFormat pix_fmt = AV_PIX_FMT_NONE, alt_pix_fmt = AV_PIX_FMT_NONE; enum AVChromaLocation chroma_sample_location = AVCHROMA_LOC_UNSPECIFIED; AVStream *st; enum AVFieldOrder field_order; for (i = 0; i < MAX_YUV4_HEADER; i++) { header[i] = avio_r8(pb); if (header[i] == '\n') { header[i + 1] = 0x20; // Add a space after last option. // Makes parsing "444" vs "444alpha" easier. header[i + 2] = 0; break; } } if (i == MAX_YUV4_HEADER) return -1; if (strncmp(header, Y4M_MAGIC, strlen(Y4M_MAGIC))) return -1; header_end = &header[i + 1]; // Include space for (tokstart = &header[strlen(Y4M_MAGIC) + 1]; tokstart < header_end; tokstart++) { if (*tokstart == 0x20) continue; switch (*tokstart++) { case 'W': // Width. Required. width = strtol(tokstart, &tokend, 10); tokstart = tokend; break; case 'H': // Height. Required. height = strtol(tokstart, &tokend, 10); tokstart = tokend; break; case 'C': // Color space if (strncmp("420jpeg", tokstart, 7) == 0) { pix_fmt = AV_PIX_FMT_YUV420P; chroma_sample_location = AVCHROMA_LOC_CENTER; } else if (strncmp("420mpeg2", tokstart, 8) == 0) { pix_fmt = AV_PIX_FMT_YUV420P; chroma_sample_location = AVCHROMA_LOC_LEFT; } else if (strncmp("420paldv", tokstart, 8) == 0) { pix_fmt = AV_PIX_FMT_YUV420P; chroma_sample_location = AVCHROMA_LOC_TOPLEFT; } else if (strncmp("420", tokstart, 3) == 0) { pix_fmt = AV_PIX_FMT_YUV420P; chroma_sample_location = AVCHROMA_LOC_CENTER; } else if (strncmp("411", tokstart, 3) == 0) pix_fmt = AV_PIX_FMT_YUV411P; else if (strncmp("422", tokstart, 3) == 0) pix_fmt = AV_PIX_FMT_YUV422P; else if (strncmp("444alpha", tokstart, 8) == 0 ) { av_log(s, AV_LOG_ERROR, "Cannot handle 4:4:4:4 " "YUV4MPEG stream.\n"); return -1; } else if (strncmp("444", tokstart, 3) == 0) pix_fmt = AV_PIX_FMT_YUV444P; else if (strncmp("mono", tokstart, 4) == 0) { pix_fmt = AV_PIX_FMT_GRAY8; } else { av_log(s, AV_LOG_ERROR, "YUV4MPEG stream contains an unknown " "pixel format.\n"); return -1; } while (tokstart < header_end && *tokstart != 0x20) tokstart++; break; case 'I': // Interlace type switch (*tokstart++){ case '?': field_order = AV_FIELD_UNKNOWN; break; case 'p': field_order = AV_FIELD_PROGRESSIVE; break; case 't': field_order = AV_FIELD_TT; break; case 'b': field_order = AV_FIELD_BB; break; case 'm': av_log(s, AV_LOG_ERROR, "YUV4MPEG stream contains mixed " "interlaced and non-interlaced frames.\n"); return -1; default: av_log(s, AV_LOG_ERROR, "YUV4MPEG has invalid header.\n"); return -1; } break; case 'F': // Frame rate sscanf(tokstart, "%d:%d", &raten, &rated); // 0:0 if unknown while (tokstart < header_end && *tokstart != 0x20) tokstart++; break; case 'A': // Pixel aspect sscanf(tokstart, "%d:%d", &aspectn, &aspectd); // 0:0 if unknown while (tokstart < header_end && *tokstart != 0x20) tokstart++; break; case 'X': // Vendor extensions if (strncmp("YSCSS=", tokstart, 6) == 0) { // Older nonstandard pixel format representation tokstart += 6; if (strncmp("420JPEG", tokstart, 7) == 0) alt_pix_fmt = AV_PIX_FMT_YUV420P; else if (strncmp("420MPEG2", tokstart, 8) == 0) alt_pix_fmt = AV_PIX_FMT_YUV420P; else if (strncmp("420PALDV", tokstart, 8) == 0) alt_pix_fmt = AV_PIX_FMT_YUV420P; else if (strncmp("411", tokstart, 3) == 0) alt_pix_fmt = AV_PIX_FMT_YUV411P; else if (strncmp("422", tokstart, 3) == 0) alt_pix_fmt = AV_PIX_FMT_YUV422P; else if (strncmp("444", tokstart, 3) == 0) alt_pix_fmt = AV_PIX_FMT_YUV444P; } while (tokstart < header_end && *tokstart != 0x20) tokstart++; break; } } if (width == -1 || height == -1) { av_log(s, AV_LOG_ERROR, "YUV4MPEG has invalid header.\n"); return -1; } if (pix_fmt == AV_PIX_FMT_NONE) { if (alt_pix_fmt == AV_PIX_FMT_NONE) pix_fmt = AV_PIX_FMT_YUV420P; else pix_fmt = alt_pix_fmt; } if (raten <= 0 || rated <= 0) { // Frame rate unknown raten = 25; rated = 1; } if (aspectn == 0 && aspectd == 0) { // Pixel aspect unknown aspectd = 1; } st = avformat_new_stream(s, NULL); if (!st) return AVERROR(ENOMEM); st->codec->width = width; st->codec->height = height; av_reduce(&raten, &rated, raten, rated, (1UL << 31) - 1); avpriv_set_pts_info(st, 64, rated, raten); st->avg_frame_rate = av_inv_q(st->time_base); st->codec->pix_fmt = pix_fmt; st->codec->codec_type = AVMEDIA_TYPE_VIDEO; st->codec->codec_id = AV_CODEC_ID_RAWVIDEO; st->sample_aspect_ratio = (AVRational){ aspectn, aspectd }; st->codec->chroma_sample_location = chroma_sample_location; st->codec->field_order = field_order; return 0; }