FFmpeg/libavformat/yuv4mpegdec.c

/*
 * YUV4MPEG demuxer
 * Copyright (c) 2001, 2002, 2003 Fabrice Bellard
 *
 * This file is part of Libav.
 *
 * Libav is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * Libav is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with Libav; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include "avformat.h"
#include "internal.h"
#include "yuv4mpeg.h"

/* Header size increased to allow room for optional flags */
#define MAX_YUV4_HEADER 80
#define MAX_FRAME_HEADER 80

struct frame_attributes {
    int interlaced_frame;
    int top_field_first;
};

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;
    struct frame_attributes *s1 = s->priv_data;

    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;

    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 = 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 '?':
                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 = 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;

    return 0;
}

static int yuv4_read_packet(AVFormatContext *s, AVPacket *pkt)
{
    int i;
    char header[MAX_FRAME_HEADER+1];
    int packet_size, width, height, ret;
    AVStream *st = s->streams[0];
    struct frame_attributes *s1 = s->priv_data;

    for (i = 0; i < MAX_FRAME_HEADER; i++) {
        header[i] = avio_r8(s->pb);
        if (header[i] == '\n') {
            header[i + 1] = 0;
            break;
        }
    }
    if (s->pb->error)
        return s->pb->error;
    else if (s->pb->eof_reached)
        return AVERROR_EOF;
    else if (i == MAX_FRAME_HEADER)
        return AVERROR_INVALIDDATA;

    if (strncmp(header, Y4M_FRAME_MAGIC, strlen(Y4M_FRAME_MAGIC)))
        return AVERROR_INVALIDDATA;

    width  = st->codec->width;
    height = st->codec->height;

    packet_size = avpicture_get_size(st->codec->pix_fmt, width, height);
    if (packet_size < 0)
        return packet_size;

    ret = av_get_packet(s->pb, pkt, packet_size);
    if (ret < 0)
        return ret;
    else if (ret != packet_size)
        return s->pb->eof_reached ? AVERROR_EOF : AVERROR(EIO);

    if (st->codec->coded_frame) {
        st->codec->coded_frame->interlaced_frame = s1->interlaced_frame;
        st->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;
}

AVInputFormat ff_yuv4mpegpipe_demuxer = {
    .name           = "yuv4mpegpipe",
    .long_name      = NULL_IF_CONFIG_SMALL("YUV4MPEG pipe"),
    .priv_data_size = sizeof(struct frame_attributes),
    .read_probe     = yuv4_probe,
    .read_header    = yuv4_read_header,
    .read_packet    = yuv4_read_packet,
    .extensions     = "y4m",
};