FFmpeg: libavformat/yuv4mpeg.c Source File

00001 /*
00002  * YUV4MPEG format
00003  * Copyright (c) 2001, 2002, 2003 Fabrice Bellard
00004  *
00005  * This file is part of FFmpeg.
00006  *
00007  * FFmpeg is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * FFmpeg is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with FFmpeg; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 #include "avformat.h"
00022 #include "internal.h"
00023 #include "libavutil/pixdesc.h"
00024 
00025 #define Y4M_MAGIC "YUV4MPEG2"
00026 #define Y4M_FRAME_MAGIC "FRAME"
00027 #define Y4M_LINE_MAX 256
00028 
00029 struct frame_attributes {
00030     int interlaced_frame;
00031     int top_field_first;
00032 };
00033 
00034 #if CONFIG_YUV4MPEGPIPE_MUXER
00035 static int yuv4_generate_header(AVFormatContext *s, char* buf)
00036 {
00037     AVStream *st;
00038     int width, height;
00039     int raten, rated, aspectn, aspectd, n;
00040     char inter;
00041     const char *colorspace = "";
00042 
00043     st     = s->streams[0];
00044     width  = st->codec->width;
00045     height = st->codec->height;
00046 
00047     av_reduce(&raten, &rated, st->codec->time_base.den,
00048               st->codec->time_base.num, (1UL << 31) - 1);
00049 
00050     aspectn = st->sample_aspect_ratio.num;
00051     aspectd = st->sample_aspect_ratio.den;
00052 
00053     if (aspectn == 0 && aspectd == 1)
00054         aspectd = 0;  // 0:0 means unknown
00055 
00056     inter = 'p'; /* progressive is the default */
00057     if (st->codec->coded_frame && st->codec->coded_frame->interlaced_frame)
00058         inter = st->codec->coded_frame->top_field_first ? 't' : 'b';
00059 
00060     switch (st->codec->pix_fmt) {
00061     case PIX_FMT_GRAY8:
00062         colorspace = " Cmono";
00063         break;
00064     case PIX_FMT_GRAY16:
00065         colorspace = " Cmono16";
00066         break;
00067     case PIX_FMT_YUV411P:
00068         colorspace = " C411 XYSCSS=411";
00069         break;
00070     case PIX_FMT_YUV420P:
00071         switch (st->codec->chroma_sample_location) {
00072         case AVCHROMA_LOC_TOPLEFT: colorspace = " C420paldv XYSCSS=420PALDV"; break;
00073         case AVCHROMA_LOC_LEFT:    colorspace = " C420mpeg2 XYSCSS=420MPEG2"; break;
00074         default:                   colorspace = " C420jpeg XYSCSS=420JPEG";   break;
00075         }
00076         break;
00077     case PIX_FMT_YUV422P:
00078         colorspace = " C422 XYSCSS=422";
00079         break;
00080     case PIX_FMT_YUV444P:
00081         colorspace = " C444 XYSCSS=444";
00082         break;
00083     case PIX_FMT_YUV420P9:
00084         colorspace = " C420p9 XYSCSS=420P9";
00085         break;
00086     case PIX_FMT_YUV422P9:
00087         colorspace = " C422p9 XYSCSS=422P9";
00088         break;
00089     case PIX_FMT_YUV444P9:
00090         colorspace = " C444p9 XYSCSS=444P9";
00091         break;
00092     case PIX_FMT_YUV420P10:
00093         colorspace = " C420p10 XYSCSS=420P10";
00094         break;
00095     case PIX_FMT_YUV422P10:
00096         colorspace = " C422p10 XYSCSS=422P10";
00097         break;
00098     case PIX_FMT_YUV444P10:
00099         colorspace = " C444p10 XYSCSS=444P10";
00100         break;
00101     case PIX_FMT_YUV420P16:
00102         colorspace = " C420p16 XYSCSS=420P16";
00103         break;
00104     case PIX_FMT_YUV422P16:
00105         colorspace = " C422p16 XYSCSS=422P16";
00106         break;
00107     case PIX_FMT_YUV444P16:
00108         colorspace = " C444p16 XYSCSS=444P16";
00109         break;
00110     }
00111 
00112     /* construct stream header, if this is the first frame */
00113     n = snprintf(buf, Y4M_LINE_MAX, "%s W%d H%d F%d:%d I%c A%d:%d%s\n",
00114                  Y4M_MAGIC, width, height, raten, rated, inter,
00115                  aspectn, aspectd, colorspace);
00116 
00117     return n;
00118 }
00119 
00120 static int yuv4_write_packet(AVFormatContext *s, AVPacket *pkt)
00121 {
00122     AVStream *st = s->streams[pkt->stream_index];
00123     AVIOContext *pb = s->pb;
00124     AVPicture *picture;
00125     int* first_pkt = s->priv_data;
00126     int width, height, h_chroma_shift, v_chroma_shift;
00127     int i;
00128     char buf2[Y4M_LINE_MAX + 1];
00129     char buf1[20];
00130     uint8_t *ptr, *ptr1, *ptr2;
00131 
00132     picture = (AVPicture *)pkt->data;
00133 
00134     /* for the first packet we have to output the header as well */
00135     if (*first_pkt) {
00136         *first_pkt = 0;
00137         if (yuv4_generate_header(s, buf2) < 0) {
00138             av_log(s, AV_LOG_ERROR,
00139                    "Error. YUV4MPEG stream header write failed.\n");
00140             return AVERROR(EIO);
00141         } else {
00142             avio_write(pb, buf2, strlen(buf2));
00143         }
00144     }
00145 
00146     /* construct frame header */
00147 
00148     snprintf(buf1, sizeof(buf1), "%s\n", Y4M_FRAME_MAGIC);
00149     avio_write(pb, buf1, strlen(buf1));
00150 
00151     width  = st->codec->width;
00152     height = st->codec->height;
00153 
00154     ptr = picture->data[0];
00155 
00156     switch (st->codec->pix_fmt) {
00157     case PIX_FMT_GRAY8:
00158     case PIX_FMT_YUV411P:
00159     case PIX_FMT_YUV420P:
00160     case PIX_FMT_YUV422P:
00161     case PIX_FMT_YUV444P:
00162         break;
00163     case PIX_FMT_GRAY16:
00164     case PIX_FMT_YUV420P9:
00165     case PIX_FMT_YUV422P9:
00166     case PIX_FMT_YUV444P9:
00167     case PIX_FMT_YUV420P10:
00168     case PIX_FMT_YUV422P10:
00169     case PIX_FMT_YUV444P10:
00170     case PIX_FMT_YUV420P16:
00171     case PIX_FMT_YUV422P16:
00172     case PIX_FMT_YUV444P16:
00173         width *= 2;
00174         break;
00175     default:
00176         av_log(s, AV_LOG_ERROR, "The pixel format '%s' is not supported.\n",
00177                av_get_pix_fmt_name(st->codec->pix_fmt));
00178         return AVERROR(EINVAL);
00179     }
00180 
00181     for (i = 0; i < height; i++) {
00182         avio_write(pb, ptr, width);
00183         ptr += picture->linesize[0];
00184     }
00185 
00186     if (st->codec->pix_fmt != PIX_FMT_GRAY8 &&
00187         st->codec->pix_fmt != PIX_FMT_GRAY16) {
00188         // Adjust for smaller Cb and Cr planes
00189         avcodec_get_chroma_sub_sample(st->codec->pix_fmt, &h_chroma_shift,
00190                                       &v_chroma_shift);
00191         width  >>= h_chroma_shift;
00192         height >>= v_chroma_shift;
00193 
00194         ptr1 = picture->data[1];
00195         ptr2 = picture->data[2];
00196         for (i = 0; i < height; i++) {     /* Cb */
00197             avio_write(pb, ptr1, width);
00198             ptr1 += picture->linesize[1];
00199         }
00200         for (i = 0; i < height; i++) {     /* Cr */
00201             avio_write(pb, ptr2, width);
00202             ptr2 += picture->linesize[2];
00203         }
00204     }
00205 
00206     avio_flush(pb);
00207     return 0;
00208 }
00209 
00210 static int yuv4_write_header(AVFormatContext *s)
00211 {
00212     int *first_pkt = s->priv_data;
00213 
00214     if (s->nb_streams != 1)
00215         return AVERROR(EIO);
00216 
00217     if (s->streams[0]->codec->codec_id != CODEC_ID_RAWVIDEO) {
00218         av_log(s, AV_LOG_ERROR,
00219                "A non-rawvideo stream was selected, but yuv4mpeg only handles rawvideo streams\n");
00220         return AVERROR(EINVAL);
00221     }
00222 
00223     switch (s->streams[0]->codec->pix_fmt) {
00224     case PIX_FMT_YUV411P:
00225         av_log(s, AV_LOG_WARNING, "Warning: generating rarely used 4:1:1 YUV "
00226                "stream, some mjpegtools might not work.\n");
00227         break;
00228     case PIX_FMT_GRAY8:
00229     case PIX_FMT_GRAY16:
00230     case PIX_FMT_YUV420P:
00231     case PIX_FMT_YUV422P:
00232     case PIX_FMT_YUV444P:
00233         break;
00234     case PIX_FMT_YUV420P9:
00235     case PIX_FMT_YUV422P9:
00236     case PIX_FMT_YUV444P9:
00237     case PIX_FMT_YUV420P10:
00238     case PIX_FMT_YUV422P10:
00239     case PIX_FMT_YUV444P10:
00240     case PIX_FMT_YUV420P16:
00241     case PIX_FMT_YUV422P16:
00242     case PIX_FMT_YUV444P16:
00243         if (s->streams[0]->codec->strict_std_compliance >= FF_COMPLIANCE_NORMAL) {
00244             av_log(s, AV_LOG_ERROR, "'%s' is not a official yuv4mpegpipe pixel format. "
00245                    "Use '-strict -1' to encode to this pixel format.\n",
00246                    av_get_pix_fmt_name(s->streams[0]->codec->pix_fmt));
00247             return AVERROR(EINVAL);
00248         }
00249         av_log(s, AV_LOG_WARNING, "Warning: generating non standart YUV stream. "
00250                "Mjpegtools will not work.\n");
00251         break;
00252     default:
00253         av_log(s, AV_LOG_ERROR, "ERROR: yuv4mpeg can only handle "
00254                "yuv444p, yuv422p, yuv420p, yuv411p and gray8 pixel formats. "
00255                "And using 'strict -1' also yuv444p9, yuv422p9, yuv420p9, "
00256                "yuv444p10, yuv422p10, yuv420p10, "
00257                "yuv444p16, yuv422p16, yuv420p16 "
00258                "and gray16 pixel formats. "
00259                "Use -pix_fmt to select one.\n");
00260         return AVERROR(EIO);
00261     }
00262 
00263     *first_pkt = 1;
00264     return 0;
00265 }
00266 
00267 AVOutputFormat ff_yuv4mpegpipe_muxer = {
00268     .name              = "yuv4mpegpipe",
00269     .long_name         = NULL_IF_CONFIG_SMALL("YUV4MPEG pipe format"),
00270     .extensions        = "y4m",
00271     .priv_data_size    = sizeof(int),
00272     .audio_codec       = CODEC_ID_NONE,
00273     .video_codec       = CODEC_ID_RAWVIDEO,
00274     .write_header      = yuv4_write_header,
00275     .write_packet      = yuv4_write_packet,
00276     .flags             = AVFMT_RAWPICTURE,
00277 };
00278 #endif
00279 
00280 /* Header size increased to allow room for optional flags */
00281 #define MAX_YUV4_HEADER 80
00282 #define MAX_FRAME_HEADER 80
00283 
00284 static int yuv4_read_header(AVFormatContext *s)
00285 {
00286     char header[MAX_YUV4_HEADER + 10];  // Include headroom for
00287                                         // the longest option
00288     char *tokstart, *tokend, *header_end;
00289     int i;
00290     AVIOContext *pb = s->pb;
00291     int width = -1, height  = -1, raten   = 0,
00292         rated =  0, aspectn =  0, aspectd = 0;
00293     enum PixelFormat pix_fmt = PIX_FMT_NONE, alt_pix_fmt = PIX_FMT_NONE;
00294     enum AVChromaLocation chroma_sample_location = AVCHROMA_LOC_UNSPECIFIED;
00295     AVStream *st;
00296     struct frame_attributes *s1 = s->priv_data;
00297 
00298     for (i = 0; i < MAX_YUV4_HEADER; i++) {
00299         header[i] = avio_r8(pb);
00300         if (header[i] == '\n') {
00301             header[i + 1] = 0x20;  // Add a space after last option.
00302                                    // Makes parsing "444" vs "444alpha" easier.
00303             header[i + 2] = 0;
00304             break;
00305         }
00306     }
00307     if (i == MAX_YUV4_HEADER)
00308         return -1;
00309     if (strncmp(header, Y4M_MAGIC, strlen(Y4M_MAGIC)))
00310         return -1;
00311 
00312     s1->interlaced_frame = 0;
00313     s1->top_field_first = 0;
00314     header_end = &header[i + 1]; // Include space
00315     for (tokstart = &header[strlen(Y4M_MAGIC) + 1];
00316          tokstart < header_end; tokstart++) {
00317         if (*tokstart == 0x20)
00318             continue;
00319         switch (*tokstart++) {
00320         case 'W': // Width. Required.
00321             width    = strtol(tokstart, &tokend, 10);
00322             tokstart = tokend;
00323             break;
00324         case 'H': // Height. Required.
00325             height   = strtol(tokstart, &tokend, 10);
00326             tokstart = tokend;
00327             break;
00328         case 'C': // Color space
00329             if (strncmp("420jpeg", tokstart, 7) == 0) {
00330                 pix_fmt = PIX_FMT_YUV420P;
00331                 chroma_sample_location = AVCHROMA_LOC_CENTER;
00332             } else if (strncmp("420mpeg2", tokstart, 8) == 0) {
00333                 pix_fmt = PIX_FMT_YUV420P;
00334                 chroma_sample_location = AVCHROMA_LOC_LEFT;
00335             } else if (strncmp("420paldv", tokstart, 8) == 0) {
00336                 pix_fmt = PIX_FMT_YUV420P;
00337                 chroma_sample_location = AVCHROMA_LOC_TOPLEFT;
00338             } else if (strncmp("420p16", tokstart, 6) == 0) {
00339                 pix_fmt = PIX_FMT_YUV420P16;
00340             } else if (strncmp("422p16", tokstart, 6) == 0) {
00341                 pix_fmt = PIX_FMT_YUV422P16;
00342             } else if (strncmp("444p16", tokstart, 6) == 0) {
00343                 pix_fmt = PIX_FMT_YUV444P16;
00344             } else if (strncmp("420p10", tokstart, 6) == 0) {
00345                 pix_fmt = PIX_FMT_YUV420P10;
00346             } else if (strncmp("422p10", tokstart, 6) == 0) {
00347                 pix_fmt = PIX_FMT_YUV422P10;
00348             } else if (strncmp("444p10", tokstart, 6) == 0) {
00349                 pix_fmt = PIX_FMT_YUV444P10;
00350             } else if (strncmp("420p9", tokstart, 5) == 0) {
00351                 pix_fmt = PIX_FMT_YUV420P9;
00352             } else if (strncmp("422p9", tokstart, 5) == 0) {
00353                 pix_fmt = PIX_FMT_YUV422P9;
00354             } else if (strncmp("444p9", tokstart, 5) == 0) {
00355                 pix_fmt = PIX_FMT_YUV444P9;
00356             } else if (strncmp("420", tokstart, 3) == 0) {
00357                 pix_fmt = PIX_FMT_YUV420P;
00358                 chroma_sample_location = AVCHROMA_LOC_CENTER;
00359             } else if (strncmp("411", tokstart, 3) == 0) {
00360                 pix_fmt = PIX_FMT_YUV411P;
00361             } else if (strncmp("422", tokstart, 3) == 0) {
00362                 pix_fmt = PIX_FMT_YUV422P;
00363             } else if (strncmp("444alpha", tokstart, 8) == 0 ) {
00364                 av_log(s, AV_LOG_ERROR, "Cannot handle 4:4:4:4 "
00365                        "YUV4MPEG stream.\n");
00366                 return -1;
00367             } else if (strncmp("444", tokstart, 3) == 0) {
00368                 pix_fmt = PIX_FMT_YUV444P;
00369             } else if (strncmp("mono", tokstart, 4) == 0) {
00370                 pix_fmt = PIX_FMT_GRAY8;
00371             } else if (strncmp("mono16", tokstart, 6) == 0) {
00372                 pix_fmt = PIX_FMT_GRAY16;
00373             } else {
00374                 av_log(s, AV_LOG_ERROR, "YUV4MPEG stream contains an unknown "
00375                        "pixel format.\n");
00376                 return -1;
00377             }
00378             while (tokstart < header_end && *tokstart != 0x20)
00379                 tokstart++;
00380             break;
00381         case 'I': // Interlace type
00382             switch (*tokstart++){
00383             case '?':
00384                 break;
00385             case 'p':
00386                 s1->interlaced_frame = 0;
00387                 break;
00388             case 't':
00389                 s1->interlaced_frame = 1;
00390                 s1->top_field_first = 1;
00391                 break;
00392             case 'b':
00393                 s1->interlaced_frame = 1;
00394                 s1->top_field_first = 0;
00395                 break;
00396             case 'm':
00397                 av_log(s, AV_LOG_ERROR, "YUV4MPEG stream contains mixed "
00398                        "interlaced and non-interlaced frames.\n");
00399                 return -1;
00400             default:
00401                 av_log(s, AV_LOG_ERROR, "YUV4MPEG has invalid header.\n");
00402                 return -1;
00403             }
00404             break;
00405         case 'F': // Frame rate
00406             sscanf(tokstart, "%d:%d", &raten, &rated); // 0:0 if unknown
00407             while (tokstart < header_end && *tokstart != 0x20)
00408                 tokstart++;
00409             break;
00410         case 'A': // Pixel aspect
00411             sscanf(tokstart, "%d:%d", &aspectn, &aspectd); // 0:0 if unknown
00412             while (tokstart < header_end && *tokstart != 0x20)
00413                 tokstart++;
00414             break;
00415         case 'X': // Vendor extensions
00416             if (strncmp("YSCSS=", tokstart, 6) == 0) {
00417                 // Older nonstandard pixel format representation
00418                 tokstart += 6;
00419                 if (strncmp("420JPEG", tokstart, 7) == 0)
00420                     alt_pix_fmt = PIX_FMT_YUV420P;
00421                 else if (strncmp("420MPEG2", tokstart, 8) == 0)
00422                     alt_pix_fmt = PIX_FMT_YUV420P;
00423                 else if (strncmp("420PALDV", tokstart, 8) == 0)
00424                     alt_pix_fmt = PIX_FMT_YUV420P;
00425                 else if (strncmp("420P9", tokstart, 5) == 0)
00426                     alt_pix_fmt = PIX_FMT_YUV420P9;
00427                 else if (strncmp("422P9", tokstart, 5) == 0)
00428                     alt_pix_fmt = PIX_FMT_YUV422P9;
00429                 else if (strncmp("444P9", tokstart, 5) == 0)
00430                     alt_pix_fmt = PIX_FMT_YUV444P9;
00431                 else if (strncmp("420P10", tokstart, 6) == 0)
00432                     alt_pix_fmt = PIX_FMT_YUV420P10;
00433                 else if (strncmp("422P10", tokstart, 6) == 0)
00434                     alt_pix_fmt = PIX_FMT_YUV422P10;
00435                 else if (strncmp("444P10", tokstart, 6) == 0)
00436                     alt_pix_fmt = PIX_FMT_YUV444P10;
00437                 else if (strncmp("420P16", tokstart, 6) == 0)
00438                     alt_pix_fmt = PIX_FMT_YUV420P16;
00439                 else if (strncmp("422P16", tokstart, 6) == 0)
00440                     alt_pix_fmt = PIX_FMT_YUV422P16;
00441                 else if (strncmp("444P16", tokstart, 6) == 0)
00442                     alt_pix_fmt = PIX_FMT_YUV444P16;
00443                 else if (strncmp("411", tokstart, 3) == 0)
00444                     alt_pix_fmt = PIX_FMT_YUV411P;
00445                 else if (strncmp("422", tokstart, 3) == 0)
00446                     alt_pix_fmt = PIX_FMT_YUV422P;
00447                 else if (strncmp("444", tokstart, 3) == 0)
00448                     alt_pix_fmt = PIX_FMT_YUV444P;
00449             }
00450             while (tokstart < header_end && *tokstart != 0x20)
00451                 tokstart++;
00452             break;
00453         }
00454     }
00455 
00456     if (width == -1 || height == -1) {
00457         av_log(s, AV_LOG_ERROR, "YUV4MPEG has invalid header.\n");
00458         return -1;
00459     }
00460 
00461     if (pix_fmt == PIX_FMT_NONE) {
00462         if (alt_pix_fmt == PIX_FMT_NONE)
00463             pix_fmt = PIX_FMT_YUV420P;
00464         else
00465             pix_fmt = alt_pix_fmt;
00466     }
00467 
00468     if (raten <= 0 || rated <= 0) {
00469         // Frame rate unknown
00470         raten = 25;
00471         rated = 1;
00472     }
00473 
00474     if (aspectn == 0 && aspectd == 0) {
00475         // Pixel aspect unknown
00476         aspectd = 1;
00477     }
00478 
00479     st = avformat_new_stream(s, NULL);
00480     if (!st)
00481         return AVERROR(ENOMEM);
00482     st->codec->width  = width;
00483     st->codec->height = height;
00484     av_reduce(&raten, &rated, raten, rated, (1UL << 31) - 1);
00485     avpriv_set_pts_info(st, 64, rated, raten);
00486     st->codec->pix_fmt                = pix_fmt;
00487     st->codec->codec_type             = AVMEDIA_TYPE_VIDEO;
00488     st->codec->codec_id               = CODEC_ID_RAWVIDEO;
00489     st->sample_aspect_ratio           = (AVRational){ aspectn, aspectd };
00490     st->codec->chroma_sample_location = chroma_sample_location;
00491 
00492     return 0;
00493 }
00494 
00495 static int yuv4_read_packet(AVFormatContext *s, AVPacket *pkt)
00496 {
00497     int i;
00498     char header[MAX_FRAME_HEADER+1];
00499     int packet_size, width, height;
00500     AVStream *st = s->streams[0];
00501     struct frame_attributes *s1 = s->priv_data;
00502 
00503     for (i = 0; i < MAX_FRAME_HEADER; i++) {
00504         header[i] = avio_r8(s->pb);
00505         if (header[i] == '\n') {
00506             header[i + 1] = 0;
00507             break;
00508         }
00509     }
00510     if (i == MAX_FRAME_HEADER)
00511         return -1;
00512     if (strncmp(header, Y4M_FRAME_MAGIC, strlen(Y4M_FRAME_MAGIC)))
00513         return -1;
00514 
00515     width  = st->codec->width;
00516     height = st->codec->height;
00517 
00518     packet_size = avpicture_get_size(st->codec->pix_fmt, width, height);
00519     if (packet_size < 0)
00520         return -1;
00521 
00522     if (av_get_packet(s->pb, pkt, packet_size) != packet_size)
00523         return AVERROR(EIO);
00524 
00525     if (st->codec->coded_frame) {
00526         st->codec->coded_frame->interlaced_frame = s1->interlaced_frame;
00527         st->codec->coded_frame->top_field_first  = s1->top_field_first;
00528     }
00529 
00530     pkt->stream_index = 0;
00531     return 0;
00532 }
00533 
00534 static int yuv4_probe(AVProbeData *pd)
00535 {
00536     /* check file header */
00537     if (strncmp(pd->buf, Y4M_MAGIC, sizeof(Y4M_MAGIC) - 1) == 0)
00538         return AVPROBE_SCORE_MAX;
00539     else
00540         return 0;
00541 }
00542 
00543 #if CONFIG_YUV4MPEGPIPE_DEMUXER
00544 AVInputFormat ff_yuv4mpegpipe_demuxer = {
00545     .name           = "yuv4mpegpipe",
00546     .long_name      = NULL_IF_CONFIG_SMALL("YUV4MPEG pipe format"),
00547     .priv_data_size = sizeof(struct frame_attributes),
00548     .read_probe     = yuv4_probe,
00549     .read_header    = yuv4_read_header,
00550     .read_packet    = yuv4_read_packet,
00551     .extensions     = "y4m",
00552 };
00553 #endif