[SCM] libav/experimental: isom: convert mp4 dvdsub extradata to vobsub format

[siretart at users.alioth.debian.org]

The following commit has been merged in the experimental branch:
commit 8f629a986c46f227abda1811a6ad1f449871ca35
Author: wm4 <nfxjfg at googlemail.com>
Date:   Wed Mar 12 21:18:46 2014 +0100

    isom: convert mp4 dvdsub extradata to vobsub format
    
    mp4 files embedding DVD subtitles do not use the same extradata format
    as the rest of Libav expects. The subtitle decoder in libavcodec in
    particular does not understand this format.
    
    Convert the extradata to the vobsub .idx format. mp4 stores the palette
    as binary 32 bit ints in YUV. The subtitle resolution is stored
    separately in the track header, which we access through AVStream.
    
    Signed-off-by: Anton Khirnov <anton at khirnov.net>

diff --git a/libavformat/isom.c b/libavformat/isom.c
index b3f3f95..e13f9cf 100644
--- a/libavformat/isom.c
+++ b/libavformat/isom.c
@@ -26,6 +26,7 @@
 #include "isom.h"
 #include "libavcodec/mpeg4audio.h"
 #include "libavcodec/mpegaudiodata.h"
+#include "libavutil/intreadwrite.h"
 
 /* http://www.mp4ra.org */
 /* ordered by muxing preference */
@@ -419,8 +420,60 @@ static const AVCodecTag mp4_audio_types[] = {
     { AV_CODEC_ID_NONE,   AOT_NULL },
 };
 
+static uint32_t yuv_to_rgba(uint32_t ycbcr)
+{
+    uint8_t r, g, b;
+    int y, cb, cr;
+
+    y  = (ycbcr >> 16) & 0xFF;
+    cr = (ycbcr >> 8)  & 0xFF;
+    cb =  ycbcr        & 0xFF;
+
+    b = av_clip_uint8(1.164 * (y - 16)                      + 2.018 * (cb - 128));
+    g = av_clip_uint8(1.164 * (y - 16) - 0.813 * (cr - 128) - 0.391 * (cb - 128));
+    r = av_clip_uint8(1.164 * (y - 16) + 1.596 * (cr - 128));
+
+    return (r << 16) | (g << 8) | b;
+}
+
+static int mov_rewrite_dvd_sub_extradata(AVStream *st)
+{
+    char pal_s[256];
+    char buf[256];
+    int pal_s_pos = 0;
+    uint8_t *src = st->codec->extradata;
+
+    if (st->codec->extradata_size != 64)
+        return 0;
+
+    for (int i = 0; i < 16; i++) {
+        uint32_t yuv = AV_RB32(src + i * 4);
+        uint32_t rgba = yuv_to_rgba(yuv);
+
+        snprintf(pal_s + pal_s_pos, sizeof(pal_s) - pal_s_pos, "%06x%s", rgba,
+                 i != 15 ? ", " : "");
+        pal_s_pos = strlen(pal_s);
+        if (pal_s_pos >= sizeof(pal_s))
+            return 0;
+    }
+
+    snprintf(buf, sizeof(buf), "size: %dx%d\npalette: %s\n",
+             st->codec->width, st->codec->height, pal_s);
+
+    av_freep(&st->codec->extradata);
+    st->codec->extradata_size = 0;
+    st->codec->extradata = av_mallocz(strlen(buf) + FF_INPUT_BUFFER_PADDING_SIZE);
+    if (!st->codec->extradata)
+        return AVERROR(ENOMEM);
+    st->codec->extradata_size = strlen(buf);
+    memcpy(st->codec->extradata, buf, st->codec->extradata_size);
+
+    return 0;
+}
+
 int ff_mp4_read_dec_config_descr(AVFormatContext *fc, AVStream *st, AVIOContext *pb)
 {
+    int err;
     int len, tag;
     int object_type_id = avio_r8(pb);
     avio_r8(pb); /* stream type */
@@ -460,6 +513,10 @@ int ff_mp4_read_dec_config_descr(AVFormatContext *fc, AVStream *st, AVIOContext
                                                         cfg.object_type)))
                 st->codec->codec_id = AV_CODEC_ID_AAC;
         }
+        if (st->codec->codec_id == AV_CODEC_ID_DVD_SUBTITLE) {
+            if ((err = mov_rewrite_dvd_sub_extradata(st)) < 0)
+                return err;
+        }
     }
     return 0;
 }

-- 
Libav/FFmpeg packaging