avcodec: add LSCR decoder

Fixes #4711.

Changelog

@@ -23,6 +23,7 @@ version <next>:
 - agm decoder
 - KUX demuxer
 - AV1 frame split bitstream filter
+- lscr decoder
 
 
 version 4.1:

configure

@@ -2712,6 +2712,7 @@ jpegls_decoder_select="mjpeg_decoder"
 jv_decoder_select="blockdsp"
 lagarith_decoder_select="llviddsp"
 ljpeg_encoder_select="idctdsp jpegtables mpegvideoenc"
+lscr_decoder_deps="zlib"
 magicyuv_decoder_select="llviddsp"
 magicyuv_encoder_select="llvidencdsp"
 mdec_decoder_select="blockdsp idctdsp mpegvideo"

libavcodec/Makefile

@@ -413,6 +413,7 @@ OBJS-$(CONFIG_KMVC_DECODER)            += kmvc.o
 OBJS-$(CONFIG_LAGARITH_DECODER)        += lagarith.o lagarithrac.o
 OBJS-$(CONFIG_LJPEG_ENCODER)           += ljpegenc.o mjpegenc_common.o
 OBJS-$(CONFIG_LOCO_DECODER)            += loco.o
+OBJS-$(CONFIG_LSCR_DECODER)            += png.o pngdec.o pngdsp.o
 OBJS-$(CONFIG_M101_DECODER)            += m101.o
 OBJS-$(CONFIG_MACE3_DECODER)           += mace.o
 OBJS-$(CONFIG_MACE6_DECODER)           += mace.o

libavcodec/allcodecs.c

@@ -173,6 +173,7 @@ extern AVCodec ff_kmvc_decoder;
 extern AVCodec ff_lagarith_decoder;
 extern AVCodec ff_ljpeg_encoder;
 extern AVCodec ff_loco_decoder;
+extern AVCodec ff_lscr_decoder;
 extern AVCodec ff_m101_decoder;
 extern AVCodec ff_magicyuv_encoder;
 extern AVCodec ff_magicyuv_decoder;

libavcodec/avcodec.h

@@ -455,6 +455,7 @@ enum AVCodecID {
     AV_CODEC_ID_HYMT,
     AV_CODEC_ID_ARBC,
     AV_CODEC_ID_AGM,
+    AV_CODEC_ID_LSCR,
 
     /* various PCM "codecs" */
     AV_CODEC_ID_FIRST_AUDIO = 0x10000,     ///< A dummy id pointing at the start of audio codecs

libavcodec/codec_desc.c

@@ -1712,6 +1712,13 @@ static const AVCodecDescriptor codec_descriptors[] = {
         .long_name = NULL_IF_CONFIG_SMALL("Amuse Graphics Movie"),
         .props     = AV_CODEC_PROP_LOSSY,
     },
+    {
+        .id        = AV_CODEC_ID_LSCR,
+        .type      = AVMEDIA_TYPE_VIDEO,
+        .name      = "lscr",
+        .long_name = NULL_IF_CONFIG_SMALL("LEAD Screen Capture"),
+        .props     = AV_CODEC_PROP_LOSSY,
+    },
 
     /* various PCM "codecs" */
     {

libavcodec/pngdec.c

@@ -1525,6 +1525,141 @@ end:
 }
 #endif
 
+#if CONFIG_LSCR_DECODER
+static int decode_frame_lscr(AVCodecContext *avctx,
+                             void *data, int *got_frame,
+                             AVPacket *avpkt)
+{
+    PNGDecContext *const s = avctx->priv_data;
+    GetByteContext *gb = &s->gb;
+    AVFrame *frame = data;
+    int ret, nb_blocks, offset = 0;
+
+    bytestream2_init(gb, avpkt->data, avpkt->size);
+
+    if ((ret = ff_get_buffer(avctx, frame, AV_GET_BUFFER_FLAG_REF)) < 0)
+        return ret;
+
+    nb_blocks = bytestream2_get_le16(gb);
+
+    if (s->last_picture.f->data[0]) {
+        ret = av_frame_copy(frame, s->last_picture.f);
+        if (ret < 0)
+            return ret;
+    }
+
+    for (int b = 0; b < nb_blocks; b++) {
+        int x, y, x2, y2, w, h, left;
+        uint32_t csize, size;
+
+        s->zstream.zalloc = ff_png_zalloc;
+        s->zstream.zfree  = ff_png_zfree;
+        s->zstream.opaque = NULL;
+
+        if ((ret = inflateInit(&s->zstream)) != Z_OK) {
+            av_log(avctx, AV_LOG_ERROR, "inflateInit returned error %d\n", ret);
+            ret = AVERROR_EXTERNAL;
+            goto end;
+        }
+
+        bytestream2_seek(gb, 2 + b * 12, SEEK_SET);
+
+        x = bytestream2_get_le16(gb);
+        y = bytestream2_get_le16(gb);
+        x2 = bytestream2_get_le16(gb);
+        y2 = bytestream2_get_le16(gb);
+        s->width  = s->cur_w = w = x2-x;
+        s->height = s->cur_h = h = y2-y;
+
+        if (w <= 0 || x < 0 || x >= avctx->width || w + x > avctx->width ||
+            h <= 0 || y < 0 || y >= avctx->height || h + y > avctx->height) {
+            ret = AVERROR_INVALIDDATA;
+            goto end;
+        }
+
+        size = bytestream2_get_le32(gb);
+
+        frame->key_frame = (nb_blocks == 1) &&
+                           (w == avctx->width) &&
+                           (h == avctx->height) &&
+                           (x == 0) && (y == 0);
+
+        bytestream2_seek(gb, 2 + nb_blocks * 12 + offset, SEEK_SET);
+        csize = bytestream2_get_be32(gb);
+        if (bytestream2_get_le32(gb) != MKTAG('I', 'D', 'A', 'T')) {
+            ret = AVERROR_INVALIDDATA;
+            goto end;
+        }
+
+        offset += size;
+        left = size;
+
+        s->y                 = 0;
+        s->row_size          = w * 3;
+
+        av_fast_padded_malloc(&s->buffer, &s->buffer_size, s->row_size + 16);
+        if (!s->buffer) {
+            ret = AVERROR(ENOMEM);
+            goto end;
+        }
+
+        av_fast_padded_malloc(&s->last_row, &s->last_row_size, s->row_size);
+        if (!s->last_row) {
+            ret = AVERROR(ENOMEM);
+            goto end;
+        }
+
+        s->crow_size         = w * 3 + 1;
+        s->crow_buf          = s->buffer + 15;
+        s->zstream.avail_out = s->crow_size;
+        s->zstream.next_out  = s->crow_buf;
+        s->image_buf         = frame->data[0] + (avctx->height - y - 1) * frame->linesize[0] + x * 3;
+        s->image_linesize    =-frame->linesize[0];
+        s->bpp               = 3;
+        s->pic_state         = 0;
+
+        while (left > 16) {
+            ret = png_decode_idat(s, csize);
+            if (ret < 0)
+                goto end;
+            left -= csize + 16;
+            if (left > 16) {
+                bytestream2_skip(gb, 4);
+                csize = bytestream2_get_be32(gb);
+                if (bytestream2_get_le32(gb) != MKTAG('I', 'D', 'A', 'T')) {
+                    ret = AVERROR_INVALIDDATA;
+                    goto end;
+                }
+            }
+        }
+
+        inflateEnd(&s->zstream);
+    }
+
+    frame->pict_type = frame->key_frame ? AV_PICTURE_TYPE_I : AV_PICTURE_TYPE_P;
+
+    av_frame_unref(s->last_picture.f);
+    if ((ret = av_frame_ref(s->last_picture.f, frame)) < 0)
+        return ret;
+
+    *got_frame = 1;
+end:
+    inflateEnd(&s->zstream);
+
+    if (ret < 0)
+        return ret;
+    return avpkt->size;
+}
+
+static void decode_flush(AVCodecContext *avctx)
+{
+    PNGDecContext *s = avctx->priv_data;
+
+    av_frame_unref(s->last_picture.f);
+}
+
+#endif
+
 #if HAVE_THREADS
 static int update_thread_context(AVCodecContext *dst, const AVCodecContext *src)
 {
@@ -1581,6 +1716,9 @@ static av_cold int png_dec_init(AVCodecContext *avctx)
 
     avctx->color_range = AVCOL_RANGE_JPEG;
 
+    if (avctx->codec_id == AV_CODEC_ID_LSCR)
+        avctx->pix_fmt = AV_PIX_FMT_BGR24;
+
     s->avctx = avctx;
     s->previous_picture.f = av_frame_alloc();
     s->last_picture.f = av_frame_alloc();
@@ -1653,3 +1791,19 @@ AVCodec ff_png_decoder = {
     .caps_internal  = FF_CODEC_CAP_SKIP_FRAME_FILL_PARAM | FF_CODEC_CAP_INIT_THREADSAFE,
 };
 #endif
+
+#if CONFIG_LSCR_DECODER
+AVCodec ff_lscr_decoder = {
+    .name           = "lscr",
+    .long_name      = NULL_IF_CONFIG_SMALL("LEAD Screen Capture"),
+    .type           = AVMEDIA_TYPE_VIDEO,
+    .id             = AV_CODEC_ID_LSCR,
+    .priv_data_size = sizeof(PNGDecContext),
+    .init           = png_dec_init,
+    .close          = png_dec_end,
+    .decode         = decode_frame_lscr,
+    .flush          = decode_flush,
+    .capabilities   = AV_CODEC_CAP_DR1 /*| AV_CODEC_CAP_DRAW_HORIZ_BAND*/,
+    .caps_internal  = FF_CODEC_CAP_SKIP_FRAME_FILL_PARAM | FF_CODEC_CAP_INIT_THREADSAFE,
+};
+#endif

libavcodec/version.h

@@ -28,7 +28,7 @@
 #include "libavutil/version.h"
 
 #define LIBAVCODEC_VERSION_MAJOR  58
-#define LIBAVCODEC_VERSION_MINOR  50
+#define LIBAVCODEC_VERSION_MINOR  51
 #define LIBAVCODEC_VERSION_MICRO 100
 
 #define LIBAVCODEC_VERSION_INT  AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \

libavformat/riff.c

@@ -485,6 +485,7 @@ const AVCodecTag ff_codec_bmp_tags[] = {
     { AV_CODEC_ID_AGM,          MKTAG('A', 'G', 'M', '5') },
     { AV_CODEC_ID_AGM,          MKTAG('A', 'G', 'M', '6') },
     { AV_CODEC_ID_AGM,          MKTAG('A', 'G', 'M', '7') },
+    { AV_CODEC_ID_LSCR,         MKTAG('L', 'S', 'C', 'R') },
     { AV_CODEC_ID_NONE,         0 }
 };