+static int yuv4_read_header(AVFormatContext *s, AVFormatParameters *ap)
+{
+ char header[MAX_YUV4_HEADER+10]; // Include headroom for the longest option
+ char *tokstart,*tokend,*header_end;
+ int i;
+ ByteIOContext *pb = s->pb;
+ int width=-1, height=-1, raten=0, rated=0, aspectn=0, aspectd=0;
+ enum PixelFormat pix_fmt=PIX_FMT_NONE,alt_pix_fmt=PIX_FMT_NONE;
+ AVStream *st;
+ struct frame_attributes *s1 = s->priv_data;
+
+ for (i=0; i<MAX_YUV4_HEADER; i++) {
+ header[i] = get_byte(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;
+
+ s1->interlaced_frame = 0;
+ s1->top_field_first = 0;
+ 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 = PIX_FMT_YUV420P;
+ else if (strncmp("420mpeg2",tokstart,8)==0)
+ pix_fmt = PIX_FMT_YUV420P;
+ else if (strncmp("420paldv", tokstart, 8)==0)
+ pix_fmt = PIX_FMT_YUV420P;
+ else if (strncmp("411", tokstart, 3)==0)
+ pix_fmt = PIX_FMT_YUV411P;
+ else if (strncmp("422", tokstart, 3)==0)
+ pix_fmt = 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 = PIX_FMT_YUV444P;
+ else if (strncmp("mono",tokstart, 4)==0) {
+ pix_fmt = 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 '?':
+ break;
+ case 'p':
+ s1->interlaced_frame=0;
+ break;
+ case 't':
+ s1->interlaced_frame=1;
+ s1->top_field_first=1;
+ break;
+ case 'b':
+ s1->interlaced_frame=1;
+ s1->top_field_first=0;
+ 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=PIX_FMT_YUV420P;
+ else if (strncmp("420MPEG2",tokstart,8)==0)
+ alt_pix_fmt=PIX_FMT_YUV420P;
+ else if (strncmp("420PALDV",tokstart,8)==0)
+ alt_pix_fmt=PIX_FMT_YUV420P;
+ else if (strncmp("411",tokstart,3)==0)
+ alt_pix_fmt=PIX_FMT_YUV411P;
+ else if (strncmp("422",tokstart,3)==0)
+ alt_pix_fmt=PIX_FMT_YUV422P;
+ else if (strncmp("444",tokstart,3)==0)
+ alt_pix_fmt=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 == PIX_FMT_NONE) {
+ if (alt_pix_fmt == PIX_FMT_NONE)
+ pix_fmt = 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 = av_new_stream(s, 0);
+ if(!st)
+ return AVERROR(ENOMEM);
+ st->codec->width = width;
+ st->codec->height = height;
+ av_reduce(&raten, &rated, raten, rated, (1UL<<31)-1);
+ av_set_pts_info(st, 64, rated, raten);
+ st->codec->pix_fmt = pix_fmt;
+ st->codec->codec_type = CODEC_TYPE_VIDEO;
+ st->codec->codec_id = CODEC_ID_RAWVIDEO;
+ st->sample_aspect_ratio= (AVRational){aspectn, aspectd};
+
+ return 0;
+}
+
+static int yuv4_read_packet(AVFormatContext *s, AVPacket *pkt)
+{
+ int i;
+ char header[MAX_FRAME_HEADER+1];
+ int packet_size, width, height;
+ AVStream *st = s->streams[0];
+ struct frame_attributes *s1 = s->priv_data;
+
+ for (i=0; i<MAX_FRAME_HEADER; i++) {
+ header[i] = get_byte(s->pb);
+ if (header[i] == '\n') {
+ header[i+1] = 0;
+ break;
+ }
+ }
+ if (i == MAX_FRAME_HEADER) return -1;
+ if (strncmp(header, Y4M_FRAME_MAGIC, strlen(Y4M_FRAME_MAGIC))) return -1;
+
+ width = st->codec->width;
+ height = st->codec->height;
+
+ packet_size = avpicture_get_size(st->codec->pix_fmt, width, height);
+ if (packet_size < 0)
+ return -1;
+
+ if (av_get_packet(s->pb, pkt, packet_size) != packet_size)
+ return AVERROR(EIO);
+
+ if (s->streams[0]->codec->coded_frame) {
+ s->streams[0]->codec->coded_frame->interlaced_frame = s1->interlaced_frame;
+ s->streams[0]->codec->coded_frame->top_field_first = s1->top_field_first;
+ }
+
+ pkt->stream_index = 0;
+ return 0;
+}
+
+static int yuv4_probe(AVProbeData *pd)
+{
+ /* check file header */
+ if (strncmp(pd->buf, Y4M_MAGIC, sizeof(Y4M_MAGIC)-1)==0)
+ return AVPROBE_SCORE_MAX;
+ else
+ return 0;
+}
+
+#if CONFIG_YUV4MPEGPIPE_DEMUXER
+AVInputFormat yuv4mpegpipe_demuxer = {
+ "yuv4mpegpipe",
+ NULL_IF_CONFIG_SMALL("YUV4MPEG pipe format"),
+ sizeof(struct frame_attributes),
+ yuv4_probe,
+ yuv4_read_header,
+ yuv4_read_packet,
+ .extensions = "y4m"
+};
+#endif