[FFmpeg-devel] [PATCH 2/2] lavc: support subtitles charset conversion.

Clément Bœsch ubitux at gmail.com
Mon Jan 7 18:13:47 CET 2013


TODO: bump lavc micro
---
 Changelog                    |   2 +
 configure                    |   2 +
 libavcodec/avcodec.h         |  18 ++++++++
 libavcodec/options_table.h   |   1 +
 libavcodec/utils.c           | 108 +++++++++++++++++++++++++++++++++++++++++--
 libavformat/assdec.c         |   1 +
 libavformat/tedcaptionsdec.c |   1 +
 libavformat/webvttdec.c      |   1 +
 8 files changed, 131 insertions(+), 3 deletions(-)

diff --git a/Changelog b/Changelog
index 1a2e96a..42a38c8 100644
--- a/Changelog
+++ b/Changelog
@@ -3,6 +3,8 @@ releases are sorted from youngest to oldest.
 
 version <next>:
 
+- Subtitles character re-encoding
+
 
 version 1.1:
 
diff --git a/configure b/configure
index 89e076f..1b119e8 100755
--- a/configure
+++ b/configure
@@ -1380,6 +1380,7 @@ HAVE_LIST="
     glob
     gnu_as
     ibm_asm
+    iconv
     inet_aton
     io_h
     isatty
@@ -3698,6 +3699,7 @@ check_func  getopt
 check_func  getrusage
 check_struct "sys/time.h sys/resource.h" "struct rusage" ru_maxrss
 check_func  gettimeofday
+check_func  iconv
 check_func  inet_aton $network_extralibs
 check_func  isatty
 check_func  localtime_r
diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
index 62f5474..be62fc8 100644
--- a/libavcodec/avcodec.h
+++ b/libavcodec/avcodec.h
@@ -3195,6 +3195,24 @@ typedef struct AVCodecContext {
      * - encoding: unused
      */
     AVDictionary *metadata;
+
+    /**
+     * Character encoding of the input subtitles file.
+     * - decoding: set by user, libavformat or libavcodec
+     * - encoding: unused
+     */
+    char *sub_charenc;
+
+    /**
+     * Subtitles character encoding mode.
+     * - decoding: set by libavformat or libavcodec, not intended to be used by user apps
+     * - encoding: unused
+     */
+    int sub_charenc_mode;
+#define FF_SUB_CHARENC_MODE_DO_NOTHING  -1  ///< do nothing (demuxer outputs a stream supposed to be already in UTF-8, or the codec is bitmap for instance)
+#define FF_SUB_CHARENC_MODE_AUTOMATIC    0  ///< libavcodec will select the mode itself
+#define FF_SUB_CHARENC_MODE_DECODER_PRE  2  ///< the AVPacket data needs to be recoded to UTF-8 before being fed to the decoder, requires iconv
+//#define FF_SUB_CHARENC_MODE_DECODER_POST 3  ///< the AVSubitle data needs to be recoded to UTF-8 after the decoder pass, requires iconv
 } AVCodecContext;
 
 AVRational av_codec_get_pkt_timebase         (const AVCodecContext *avctx);
diff --git a/libavcodec/options_table.h b/libavcodec/options_table.h
index 2a31fa6..75c1961 100644
--- a/libavcodec/options_table.h
+++ b/libavcodec/options_table.h
@@ -403,6 +403,7 @@ static const AVOption options[]={
 {"ka", "Karaoke",            0, AV_OPT_TYPE_CONST, {.i64 = AV_AUDIO_SERVICE_TYPE_KARAOKE },           INT_MIN, INT_MAX, A|E, "audio_service_type"},
 {"request_sample_fmt", "sample format audio decoders should prefer", OFFSET(request_sample_fmt), AV_OPT_TYPE_SAMPLE_FMT, {.i64=AV_SAMPLE_FMT_NONE}, -1, AV_SAMPLE_FMT_NB-1, A|D, "request_sample_fmt"},
 {"pkt_timebase", NULL, OFFSET(pkt_timebase), AV_OPT_TYPE_RATIONAL, {.dbl = 0 }, 0, INT_MAX, 0},
+{"sub_charenc", "set input text subtitles character encoding", OFFSET(sub_charenc), AV_OPT_TYPE_STRING, {.str = NULL}, CHAR_MIN, CHAR_MAX, S|D},
 {NULL},
 };
 
diff --git a/libavcodec/utils.c b/libavcodec/utils.c
index 99b2202..3e2326e 100644
--- a/libavcodec/utils.c
+++ b/libavcodec/utils.c
@@ -47,6 +47,9 @@
 #include <stdarg.h>
 #include <limits.h>
 #include <float.h>
+#if HAVE_ICONV
+# include <iconv.h>
+#endif
 
 volatile int ff_avcodec_locked;
 static int volatile entangled_thread_counter = 0;
@@ -1058,6 +1061,34 @@ int attribute_align_arg avcodec_open2(AVCodecContext *avctx, const AVCodec *code
             ret = AVERROR(EINVAL);
             goto free_and_end;
         }
+        if (avctx->sub_charenc) {
+            if (avctx->codec_type != AVMEDIA_TYPE_SUBTITLE) {
+                av_log(avctx, AV_LOG_ERROR, "Character encoding is only "
+                       "supported with subtitles codecs\n");
+                ret = AVERROR(EINVAL);
+                goto free_and_end;
+            } else if (avctx->codec_descriptor->props & AV_CODEC_PROP_BITMAP_SUB) {
+                av_log(avctx, AV_LOG_WARNING, "Codec '%s' is bitmap-based, "
+                       "subtitles character encoding will be ignored\n",
+                       avctx->codec_descriptor->name);
+                avctx->sub_charenc_mode = FF_SUB_CHARENC_MODE_DO_NOTHING;
+            } else {
+                /* input character encoding is set for a text based subtitle
+                 * codec at this point */
+                if (avctx->sub_charenc_mode == FF_SUB_CHARENC_MODE_AUTOMATIC)
+                    avctx->sub_charenc_mode = FF_SUB_CHARENC_MODE_DECODER_PRE;
+
+                if (!HAVE_ICONV && avctx->sub_charenc_mode == FF_SUB_CHARENC_MODE_DECODER_PRE) {
+                    av_log(avctx, AV_LOG_ERROR, "Character encoding subtitles "
+                           "conversion needs a libavcodec built with iconv support "
+                           "for this codec\n");
+                    ret = AVERROR(ENOSYS);
+                    goto free_and_end;
+                }
+            }
+        } else {
+            avctx->sub_charenc_mode = FF_SUB_CHARENC_MODE_DO_NOTHING;
+        }
     }
 end:
     ff_unlock_avcodec();
@@ -1816,6 +1847,68 @@ int attribute_align_arg avcodec_decode_audio4(AVCodecContext *avctx,
     return ret;
 }
 
+#define UTF8_MAX_BYTES 4 /* 5 and 6 bytes sequences should not be used */
+static int recode_subtitle(AVCodecContext *avctx,
+                           AVPacket *outpkt, const AVPacket *inpkt)
+{
+#if HAVE_ICONV
+    iconv_t cd = (iconv_t)-1;
+    int ret = 0;
+    char *inb, *outb;
+    size_t inl, outl;
+    AVPacket tmp;
+#endif
+
+    if (avctx->sub_charenc_mode != FF_SUB_CHARENC_MODE_DECODER_PRE)
+        return 0;
+
+#if HAVE_ICONV
+    cd = iconv_open("UTF-8", avctx->sub_charenc);
+    if (cd == (iconv_t)-1) {
+        av_log(avctx, AV_LOG_ERROR, "Unable to open iconv context "
+               "with input character encoding \"%s\"\n", avctx->sub_charenc);
+        ret = AVERROR(errno);
+        goto end;
+    }
+
+    inb = inpkt->data;
+    inl = inpkt->size;
+
+    if (inl >= INT_MAX / UTF8_MAX_BYTES - FF_INPUT_BUFFER_PADDING_SIZE) {
+        av_log(avctx, AV_LOG_ERROR, "Subtitles packet is too big for recoding\n");
+        ret = AVERROR(ENOMEM);
+        goto end;
+    }
+
+    ret = av_new_packet(&tmp, inl * UTF8_MAX_BYTES);
+    if (ret < 0)
+        goto end;
+    outpkt->data = tmp.data;
+    outpkt->size = tmp.size;
+    outb = outpkt->data;
+    outl = outpkt->size;
+
+    if (iconv(cd, &inb, &inl, &outb, &outl) == (size_t)-1 ||
+        iconv(cd, NULL, NULL, &outb, &outl) == (size_t)-1 ||
+        outl >= outpkt->size || inl != 0) {
+        av_log(avctx, AV_LOG_ERROR, "Unable to recode subtitle event \"%s\" "
+               "from %s to UTF-8\n", inpkt->data, avctx->sub_charenc);
+        av_free_packet(&tmp);
+        ret = AVERROR(errno);
+        goto end;
+    }
+    outpkt->size -= outl;
+    outpkt->data[outpkt->size - 1] = '\0';
+
+end:
+    if (cd != (iconv_t)-1)
+        iconv_close(cd);
+    return ret;
+#else
+    av_assert0(!"requesting subtitles recoding without iconv");
+#endif
+}
+
 int avcodec_decode_subtitle2(AVCodecContext *avctx, AVSubtitle *sub,
                              int *got_sub_ptr,
                              AVPacket *avpkt)
@@ -1831,19 +1924,28 @@ int avcodec_decode_subtitle2(AVCodecContext *avctx, AVSubtitle *sub,
     avcodec_get_subtitle_defaults(sub);
 
     if (avpkt->size) {
+        AVPacket pkt_recoded;
         AVPacket tmp = *avpkt;
         int did_split = av_packet_split_side_data(&tmp);
         //apply_param_change(avctx, &tmp);
 
-        avctx->pkt = &tmp;
+        pkt_recoded = tmp;
+        ret = recode_subtitle(avctx, &pkt_recoded, &tmp);
+        if (ret < 0) {
+            *got_sub_ptr = 0;
+        } else {
+        avctx->pkt = &pkt_recoded;
 
         if (avctx->pkt_timebase.den && avpkt->pts != AV_NOPTS_VALUE)
             sub->pts = av_rescale_q(avpkt->pts,
                                     avctx->pkt_timebase, AV_TIME_BASE_Q);
-        ret = avctx->codec->decode(avctx, sub, got_sub_ptr, &tmp);
+        ret = avctx->codec->decode(avctx, sub, got_sub_ptr, &pkt_recoded);
+        if (tmp.data != pkt_recoded.data)
+            av_free(pkt_recoded.data);
         sub->format = !(avctx->codec_descriptor->props & AV_CODEC_PROP_BITMAP_SUB);
-
         avctx->pkt = NULL;
+        }
+
         if (did_split) {
             ff_packet_free_side_data(&tmp);
             if(ret == tmp.size)
diff --git a/libavformat/assdec.c b/libavformat/assdec.c
index 35fcb51..710a171 100644
--- a/libavformat/assdec.c
+++ b/libavformat/assdec.c
@@ -93,6 +93,7 @@ static int ass_read_header(AVFormatContext *s)
     avpriv_set_pts_info(st, 64, 1, 100);
     st->codec->codec_type = AVMEDIA_TYPE_SUBTITLE;
     st->codec->codec_id= AV_CODEC_ID_SSA;
+    st->codec->sub_charenc_mode = FF_SUB_CHARENC_MODE_DO_NOTHING;
 
     header_remaining= INT_MAX;
 
diff --git a/libavformat/tedcaptionsdec.c b/libavformat/tedcaptionsdec.c
index 85bed0a..69d0d17 100644
--- a/libavformat/tedcaptionsdec.c
+++ b/libavformat/tedcaptionsdec.c
@@ -296,6 +296,7 @@ static av_cold int tedcaptions_read_header(AVFormatContext *avf)
         return AVERROR(ENOMEM);
     st->codec->codec_type     = AVMEDIA_TYPE_SUBTITLE;
     st->codec->codec_id       = CODEC_ID_TEXT;
+    st->codec->sub_charenc_mode = FF_SUB_CHARENC_MODE_DO_NOTHING;
     avpriv_set_pts_info(st, 64, 1, 1000);
     st->probe_packets = 0;
     st->start_time    = 0;
diff --git a/libavformat/webvttdec.c b/libavformat/webvttdec.c
index 694a020..42d8162 100644
--- a/libavformat/webvttdec.c
+++ b/libavformat/webvttdec.c
@@ -66,6 +66,7 @@ static int webvtt_read_header(AVFormatContext *s)
     avpriv_set_pts_info(st, 64, 1, 1000);
     st->codec->codec_type = AVMEDIA_TYPE_SUBTITLE;
     st->codec->codec_id   = AV_CODEC_ID_WEBVTT;
+    st->codec->sub_charenc_mode = FF_SUB_CHARENC_MODE_DO_NOTHING;
 
     av_bprint_init(&header, 0, AV_BPRINT_SIZE_UNLIMITED);
     av_bprint_init(&cue,    0, AV_BPRINT_SIZE_UNLIMITED);
-- 
1.8.1



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