[FFmpeg-devel] [PATCH] lavc: support subtitles charset conversion.
Clément Bœsch
ubitux at gmail.com
Fri Jan 4 06:24:16 CET 2013
On Thu, Jan 03, 2013 at 04:53:02PM +0100, Nicolas George wrote:
[...]
> > > AV_TEXT_ENCODING_MODE_POST, //< lavc must recode the decoded text
> > That sounds like the perfect place ;)
>
> Actually, no: the more I think about it, the more I believe that PRE is way
> better than POST. Unless I am mistaken, recoding before the decoder would
> work just as well for all current codecs an ASCII-compatible encodings, plus
> it will work with non-ASCII-compatible encodings just as well.
>
> The only situation where POST would be better than PRE seems to be if the
> codec mixes binary and text data (for example: U16BE line_length;
> U8 line[line_length]; repeat). And we do not have those currently.
>
> > Except that it doesn't contain the buffer size, so it can only do ASCII
> > compliant charset conversions.
>
> The problem is not just the buffer size: the decoders produce ASS markup in
> ASCII, so, for example, a line break, "\N" would become U+5C4E
> (non-existent) in UTF-16-BE (depending on the parity of the text before).
>
Indeed, you're right. New patch attached with pre-mode.
> > Note: inside the demuxer, you don't have access to the codec charset
> > (options are not yet populated). Inside the decoder that's possible.
>
> The same problem happens for the rawvideo or pcm demuxers: the frame size or
> sample rate is not available. This is solved using a private option with a
> standardized name.
>
> > I must say I have a hard time following what you actually want me to do.
> > Can you tell me more about what you want to want to expose to the user
> > first?
>
> Do you mean API user or command-line tool user?
>
I was wondering what in my patch was preventing any code evolution, so my
question was about any interface with the user.
Now that the character re-encoding is done before decoding, do you see any
design problem with it?
Note about the FIXME in the patch: we should add some kind of flags to the
codec because the recoding will obviously have unwanted behaviour with
bitmap sub packets.
--
Clément B.
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From 9f5abea45ed8750ca2cee384b65749ec64f422f2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Cl=C3=A9ment=20B=C5=93sch?= <ubitux at gmail.com>
Date: Mon, 31 Dec 2012 10:05:25 +0100
Subject: [PATCH 1/5] lavc: support subtitles recoding.
TODO: bump lavc minor
---
Changelog | 1 +
configure | 2 ++
libavcodec/avcodec.h | 7 ++++
libavcodec/options_table.h | 1 +
libavcodec/utils.c | 80 ++++++++++++++++++++++++++++++++++++++++++++--
5 files changed, 89 insertions(+), 2 deletions(-)
diff --git a/Changelog b/Changelog
index 7bea6af..0933df6 100644
--- a/Changelog
+++ b/Changelog
@@ -54,6 +54,7 @@ version <next>:
- Sony Wave64 muxer
- adobe and limelight publisher authentication in RTMP
- data: URI scheme
+- Subtitles character re-encoding
version 1.0:
diff --git a/configure b/configure
index 32f7eb1..d2b6162 100755
--- a/configure
+++ b/configure
@@ -1380,6 +1380,7 @@ HAVE_LIST="
glob
gnu_as
ibm_asm
+ iconv
inet_aton
io_h
isatty
@@ -3696,6 +3697,7 @@ 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 012a31c..060589b 100644
--- a/libavcodec/avcodec.h
+++ b/libavcodec/avcodec.h
@@ -3188,6 +3188,13 @@ typedef struct AVCodecContext {
* - encoding: unused
*/
AVDictionary *metadata;
+
+ /**
+ * Character encoding of the input subtitles file.
+ * - decoding: set by user
+ * - encoding: unused
+ */
+ char *sub_charenc;
} 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 f5ceae4..501084d 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 +1061,12 @@ int attribute_align_arg avcodec_open2(AVCodecContext *avctx, const AVCodec *code
ret = AVERROR(EINVAL);
goto free_and_end;
}
+ if (!HAVE_ICONV && avctx->codec_type == AVMEDIA_TYPE_SUBTITLE && avctx->sub_charenc) {
+ av_log(avctx, AV_LOG_ERROR, "Character encoding subtitles conversion needs "
+ "a libavcodec built with iconv support.\n");
+ ret = AVERROR(EINVAL);
+ goto free_and_end;
+ }
}
end:
ff_unlock_avcodec();
@@ -1816,6 +1825,64 @@ int attribute_align_arg avcodec_decode_audio4(AVCodecContext *avctx,
return ret;
}
+#if HAVE_ICONV
+#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)
+{
+ iconv_t cd = (iconv_t)-1;
+ int ret = 0;
+ char *inb, *outb;
+ size_t inl, outl;
+ AVPacket tmp;
+
+ if (!avctx->sub_charenc) // FIXME add a codec prop for sub codec supporting it
+ goto end;
+
+ 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;
+}
+#endif
+
int avcodec_decode_subtitle2(AVCodecContext *avctx, AVSubtitle *sub,
int *got_sub_ptr,
AVPacket *avpkt)
@@ -1831,16 +1898,25 @@ 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;
+#if HAVE_ICONV
+ if (recode_subtitle(avctx, &pkt_recoded, &tmp) < 0)
+ pkt_recoded = tmp;
+#endif
+
+ 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 = sub->num_rects && sub->rects[0]->ass;
avctx->pkt = NULL;
--
1.8.1
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