static int mov_read_tkhd(MOVContext *c, AVIOContext *pb, MOVAtom atom) { int i; int width; int height; int64_t disp_transform[2]; int display_matrix[3][3]; AVStream *st; MOVStreamContext *sc; int version; int flags; if (c->fc->nb_streams < 1) return 0; st = c->fc->streams[c->fc->nb_streams-1]; sc = st->priv_data; version = avio_r8(pb); flags = avio_rb24(pb); st->disposition |= (flags & MOV_TKHD_FLAG_ENABLED) ? AV_DISPOSITION_DEFAULT : 0; if (version == 1) { avio_rb64(pb); avio_rb64(pb); } else { avio_rb32(pb); /* creation time */ avio_rb32(pb); /* modification time */ } st->id = (int)avio_rb32(pb); /* track id (NOT 0 !)*/ avio_rb32(pb); /* reserved */ /* highlevel (considering edits) duration in movie timebase */ (version == 1) ? avio_rb64(pb) : avio_rb32(pb); avio_rb32(pb); /* reserved */ avio_rb32(pb); /* reserved */ avio_rb16(pb); /* layer */ avio_rb16(pb); /* alternate group */ avio_rb16(pb); /* volume */ avio_rb16(pb); /* reserved */ //read in the display matrix (outlined in ISO 14496-12, Section 6.2.2) // they're kept in fixed point format through all calculations // save u,v,z to store the whole matrix in the AV_PKT_DATA_DISPLAYMATRIX // side data, but the scale factor is not needed to calculate aspect ratio for (i = 0; i < 3; i++) { display_matrix[i][0] = avio_rb32(pb); // 16.16 fixed point display_matrix[i][1] = avio_rb32(pb); // 16.16 fixed point display_matrix[i][2] = avio_rb32(pb); // 2.30 fixed point } width = avio_rb32(pb); // 16.16 fixed point track width height = avio_rb32(pb); // 16.16 fixed point track height sc->width = width >> 16; sc->height = height >> 16; // save the matrix when it is not the default identity if (display_matrix[0][0] != (1 << 16) || display_matrix[1][1] != (1 << 16) || display_matrix[2][2] != (1 << 30) || display_matrix[0][1] || display_matrix[0][2] || display_matrix[1][0] || display_matrix[1][2] || display_matrix[2][0] || display_matrix[2][1]) { int i, j; av_freep(&sc->display_matrix); sc->display_matrix = av_malloc(sizeof(int32_t) * 9); if (!sc->display_matrix) return AVERROR(ENOMEM); for (i = 0; i < 3; i++) for (j = 0; j < 3; j++) sc->display_matrix[i * 3 + j] = display_matrix[j][i]; } // transform the display width/height according to the matrix // skip this if the rotation angle is 0 degrees // to keep the same scale, use [width height 1<<16] if (width && height && sc->display_matrix && av_display_rotation_get(sc->display_matrix) != 0.0f) { for (i = 0; i < 2; i++) disp_transform[i] = (int64_t) width * display_matrix[0][i] + (int64_t) height * display_matrix[1][i] + ((int64_t) display_matrix[2][i] << 16); //sample aspect ratio is new width/height divided by old width/height st->sample_aspect_ratio = av_d2q( ((double) disp_transform[0] * height) / ((double) disp_transform[1] * width), INT_MAX); } return 0; }