matroska.c

ffmpeg源码分析

                    res = AVERROR_INVALIDDATA;
                    break;
                } else if ((res = ebml_read_master(matroska, &id)) < 0)
                    break;
                videotrack = (MatroskaVideoTrack *)track;

                while (res == 0) {
                    if (!(id = ebml_peek_id(matroska, &matroska->level_up))) {
                        res = AVERROR_IO;
                        break;
                    } else if (matroska->level_up > 0) {
                        matroska->level_up--;
                        break;
                    }

                    switch (id) {
                        /* fixme, this should be one-up, but I get it here */
                        case MATROSKA_ID_TRACKDEFAULTDURATION: {
                            uint64_t num;
                            if ((res = ebml_read_uint (matroska, &id,
                                                       &num)) < 0)
                                break;
                            track->default_duration = num;
                            break;
                        }

                        /* video framerate */
                        case MATROSKA_ID_VIDEOFRAMERATE: {
                            double num;
                            if ((res = ebml_read_float(matroska, &id,
                                                       &num)) < 0)
                                break;
                            track->default_duration = 1000000000 * (1. / num);
                            break;
                        }

                        /* width of the size to display the video at */
                        case MATROSKA_ID_VIDEODISPLAYWIDTH: {
                            uint64_t num;
                            if ((res = ebml_read_uint(matroska, &id,
                                                      &num)) < 0)
                                break;
                            videotrack->display_width = num;
                            break;
                        }

                        /* height of the size to display the video at */
                        case MATROSKA_ID_VIDEODISPLAYHEIGHT: {
                            uint64_t num;
                            if ((res = ebml_read_uint(matroska, &id,
                                                      &num)) < 0)
                                break;
                            videotrack->display_height = num;
                            break;
                        }

                        /* width of the video in the file */
                        case MATROSKA_ID_VIDEOPIXELWIDTH: {
                            uint64_t num;
                            if ((res = ebml_read_uint(matroska, &id,
                                                      &num)) < 0)
                                break;
                            videotrack->pixel_width = num;
                            break;
                        }

                        /* height of the video in the file */
                        case MATROSKA_ID_VIDEOPIXELHEIGHT: {
                            uint64_t num;
                            if ((res = ebml_read_uint(matroska, &id,
                                                      &num)) < 0)
                                break;
                            videotrack->pixel_height = num;
                            break;
                        }

                        /* whether the video is interlaced */
                        case MATROSKA_ID_VIDEOFLAGINTERLACED: {
                            uint64_t num;
                            if ((res = ebml_read_uint(matroska, &id,
                                                      &num)) < 0)
                                break;
                            if (num)
                                track->flags |=
                                    MATROSKA_VIDEOTRACK_INTERLACED;
                            else
                                track->flags &=
                                    ~MATROSKA_VIDEOTRACK_INTERLACED;
                            break;
                        }

                        /* stereo mode (whether the video has two streams,
                         * where one is for the left eye and the other for
                         * the right eye, which creates a 3D-like
                         * effect) */
                        case MATROSKA_ID_VIDEOSTEREOMODE: {
                            uint64_t num;
                            if ((res = ebml_read_uint(matroska, &id,
                                                      &num)) < 0)
                                break;
                            if (num != MATROSKA_EYE_MODE_MONO &&
                                num != MATROSKA_EYE_MODE_LEFT &&
                                num != MATROSKA_EYE_MODE_RIGHT &&
                                num != MATROSKA_EYE_MODE_BOTH) {
                                av_log(matroska->ctx, AV_LOG_INFO,
                                       "Ignoring unknown eye mode 0x%x\n",
                                       (uint32_t) num);
                                break;
                            }
                            videotrack->eye_mode = num;
                            break;
                        }

                        /* aspect ratio behaviour */
                        case MATROSKA_ID_VIDEOASPECTRATIO: {
                            uint64_t num;
                            if ((res = ebml_read_uint(matroska, &id,
                                                      &num)) < 0)
                                break;
                            if (num != MATROSKA_ASPECT_RATIO_MODE_FREE &&
                                num != MATROSKA_ASPECT_RATIO_MODE_KEEP &&
                                num != MATROSKA_ASPECT_RATIO_MODE_FIXED) {
                                av_log(matroska->ctx, AV_LOG_INFO,
                                       "Ignoring unknown aspect ratio 0x%x\n",
                                       (uint32_t) num);
                                break;
                            }
                            videotrack->ar_mode = num;
                            break;
                        }

                        /* colourspace (only matters for raw video)
                         * fourcc */
                        case MATROSKA_ID_VIDEOCOLOURSPACE: {
                            uint64_t num;
                            if ((res = ebml_read_uint(matroska, &id,
                                                      &num)) < 0)
                                break;
                            videotrack->fourcc = num;
                            break;
                        }

                        default:
                            av_log(matroska->ctx, AV_LOG_INFO,
                                   "Unknown video track header entry "
                                   "0x%x - ignoring\n", id);
                            /* pass-through */

                        case EBML_ID_VOID:
                            res = ebml_read_skip(matroska);
                            break;
                    }

                    if (matroska->level_up) {
                        matroska->level_up--;
                        break;
                    }
                }
                break;
            }

            /* tracktype specific stuff for audio */
            case MATROSKA_ID_TRACKAUDIO: {
                MatroskaAudioTrack *audiotrack;
                if (track->type != MATROSKA_TRACK_TYPE_AUDIO) {
                    av_log(matroska->ctx, AV_LOG_INFO,
                           "audio data in non-audio track - ignoring\n");
                    res = AVERROR_INVALIDDATA;
                    break;
                } else if ((res = ebml_read_master(matroska, &id)) < 0)
                    break;
                audiotrack = (MatroskaAudioTrack *)track;

                while (res == 0) {
                    if (!(id = ebml_peek_id(matroska, &matroska->level_up))) {
                        res = AVERROR_IO;
                        break;
                    } else if (matroska->level_up > 0) {
                        matroska->level_up--;
                        break;
                    }

                    switch (id) {
                        /* samplerate */
                        case MATROSKA_ID_AUDIOSAMPLINGFREQ: {
                            double num;
                            if ((res = ebml_read_float(matroska, &id,
                                                       &num)) < 0)
                                break;
                            audiotrack->samplerate = num;
                            break;
                        }

                            /* bitdepth */
                        case MATROSKA_ID_AUDIOBITDEPTH: {
                            uint64_t num;
                            if ((res = ebml_read_uint(matroska, &id,
                                                      &num)) < 0)
                                break;
                            audiotrack->bitdepth = num;
                            break;
                        }

                            /* channels */
                        case MATROSKA_ID_AUDIOCHANNELS: {
                            uint64_t num;
                            if ((res = ebml_read_uint(matroska, &id,
                                                      &num)) < 0)
                                break;
                            audiotrack->channels = num;
                            break;
                        }

                        default:
                            av_log(matroska->ctx, AV_LOG_INFO,
                                   "Unknown audio track header entry "
                                   "0x%x - ignoring\n", id);
                            /* pass-through */

                        case EBML_ID_VOID:
                            res = ebml_read_skip(matroska);
                            break;
                    }

                    if (matroska->level_up) {
                        matroska->level_up--;
                        break;
                    }
                }
                break;
            }

                /* codec identifier */
            case MATROSKA_ID_CODECID: {
                char *text;
                if ((res = ebml_read_ascii(matroska, &id, &text)) < 0)
                    break;
                track->codec_id = text;
                break;
            }

                /* codec private data */
            case MATROSKA_ID_CODECPRIVATE: {
                uint8_t *data;
                int size;
                if ((res = ebml_read_binary(matroska, &id, &data, &size) < 0))
                    break;
                track->codec_priv = data;
                track->codec_priv_size = size;
                break;
            }

                /* name of the codec */
            case MATROSKA_ID_CODECNAME: {
                char *text;
                if ((res = ebml_read_utf8(matroska, &id, &text)) < 0)
                    break;
                track->codec_name = text;
                break;
            }

                /* name of this track */
            case MATROSKA_ID_TRACKNAME: {
                char *text;
                if ((res = ebml_read_utf8(matroska, &id, &text)) < 0)
                    break;
                track->name = text;
                break;
            }

                /* language (matters for audio/subtitles, mostly) */
            case MATROSKA_ID_TRACKLANGUAGE: {
                char *text;
                if ((res = ebml_read_utf8(matroska, &id, &text)) < 0)
                    break;
                track->language = text;
                break;
            }

                /* whether this is actually used */
            case MATROSKA_ID_TRACKFLAGENABLED: {
                uint64_t num;
                if ((res = ebml_read_uint(matroska, &id, &num)) < 0)
                    break;
                if (num)
                    track->flags |= MATROSKA_TRACK_ENABLED;
                else
                    track->flags &= ~MATROSKA_TRACK_ENABLED;
                break;
            }

                /* whether it's the default for this track type */
            case MATROSKA_ID_TRACKFLAGDEFAULT: {
                uint64_t num;
                if ((res = ebml_read_uint(matroska, &id, &num)) < 0)
                    break;
                if (num)
                    track->flags |= MATROSKA_TRACK_DEFAULT;
                else
                    track->flags &= ~MATROSKA_TRACK_DEFAULT;
                break;
            }

                /* lacing (like MPEG, where blocks don't end/start on frame
                 * boundaries) */
            case MATROSKA_ID_TRACKFLAGLACING: {
                uint64_t num;
                if ((res = ebml_read_uint(matroska, &id, &num)) < 0)
                    break;
                if (num)
                    track->flags |= MATROSKA_TRACK_LACING;
                else
                    track->flags &= ~MATROSKA_TRACK_LACING;
                break;
            }

                /* default length (in time) of one data block in this track */
            case MATROSKA_ID_TRACKDEFAULTDURATION: {
                uint64_t num;
                if ((res = ebml_read_uint(matroska, &id, &num)) < 0)
                    break;
                track->default_duration = num;
                break;
            }

            default:
                av_log(matroska->ctx, AV_LOG_INFO,
                       "Unknown track header entry 0x%x - ignoring\n", id);
                /* pass-through */

            case EBML_ID_VOID:
            /* we ignore these because they're nothing useful. */
            case MATROSKA_ID_CODECINFOURL:
            case MATROSKA_ID_CODECDOWNLOADURL:
            case MATROSKA_ID_TRACKMINCACHE:
            case MATROSKA_ID_TRACKMAXCACHE:
                res = ebml_read_skip(matroska);
                break;
        }

        if (matroska->level_up) {
            matroska->level_up--;
            break;
        }
    }

    return res;
}

static int
matroska_parse_tracks (MatroskaDemuxContext *matroska)
{
    int res = 0;
    uint32_t id;

    av_log(matroska->ctx, AV_LOG_DEBUG, "parsing tracks...\n");

    while (res == 0) {
        if (!(id = ebml_peek_id(matroska, &matroska->level_up))) {
            res = AVERROR_IO;
            break;
        } else if (matroska->level_up) {
            matroska->level_up--;
            break;
        }

        switch (id) {
            /* one track within the "all-tracks" header */
            case MATROSKA_ID_TRACKENTRY:
                res = matroska_add_stream(matroska);
                break;

            default:
                av_log(matroska->ctx, AV_LOG_INFO,
                       "Unknown entry 0x%x in track header\n", id);
                /* fall-through */

            case EBML_ID_VOID:
                res = ebml_read_skip(matroska);
                break;
        }

        if (matroska->level_up) {
            matroska->level_up--;
            break;
        }
    }

    return res;
}

static int
matroska_parse_index (MatroskaDemuxContext *matroska)
{
    int res = 0;
    uint32_t id;
    MatroskaDemuxIndex idx;

    av_log(matroska->ctx, AV_LOG_DEBUG, "parsing index...\n");

    while (res == 0) {
        if (!(id = ebml_peek_id(matroska, &matroska->level_up))) {
            res = AVERROR_IO;
            break;
        } else if (matroska->level_up) {
            matroska->level_up--;
            break;
        }

        switch (id) {
            /* one single index entry ('point') */
            case MATROSKA_ID_POINTENTRY: