[FFmpeg-devel] [PATCH 2/3] mpegts muxer: DVB subtitles multiple languages support

[Michael Niedermayer]

On Mon, Feb 03, 2014 at 02:11:06PM +0200, mrlika wrote:
> * restore multiple languages data from extradata to PMT table
> * setting correctly hearing empaired subtitling type
> ---
>  libavformat/mpegtsenc.c | 49 ++++++++++++++++++++++++++++++++++++-------------
>  1 file changed, 36 insertions(+), 13 deletions(-)
> 
> diff --git a/libavformat/mpegtsenc.c b/libavformat/mpegtsenc.c
> index 9b42e48..f6e2128 100644
> --- a/libavformat/mpegtsenc.c
> +++ b/libavformat/mpegtsenc.c
> @@ -377,20 +377,43 @@ static void mpegts_write_pmt(AVFormatContext *s, MpegTSService *service)
>                  const char *language = lang && strlen(lang->value) >= 3 ? lang->value : default_language;
>  
>                  if (st->codec->codec_id == AV_CODEC_ID_DVB_SUBTITLE) {
> -                    /* The descriptor tag. subtitling_descriptor */
> -                    *q++ = 0x59;
> -                    *q++ = 8;
> -                    *q++ = language[0];
> -                    *q++ = language[1];
> -                    *q++ = language[2];
> -                    *q++ = 0x10; /* normal subtitles (0x20 = if hearing pb) */
> -                    if(st->codec->extradata_size == 4) {
> -                        memcpy(q, st->codec->extradata, 4);
> -                        q += 4;
> -                    } else {
> -                        put16(&q, 1); /* page id */
> -                        put16(&q, 1); /* ancillary page id */
> +                    uint8_t *len_ptr;
> +                    int extradata_copied = 0;
> +
> +                    *q++ = 0x59; /* subtitling_descriptor */
> +                    len_ptr = q++;
> +
> +                    while (strlen(language) >= 3) {
> +                        *q++ = *language++;
> +                        *q++ = *language++;
> +                        *q++ = *language++;
> +                        /* Skip comma */
> +                        if (*language != '\0')
> +                            language++;
> +
> +                        if (st->codec->extradata_size - extradata_copied >= 5) {
> +                            *q++ = st->codec->extradata[extradata_copied + 4]; /* subtitling_type */
> +                            memcpy(q, st->codec->extradata + extradata_copied, 4); /* composition_page_id and ancillary_page_id */
> +                            extradata_copied += 5;
> +                            q += 4;
> +                        } else {
> +                            /* subtitling_type:
> +                             * 0x10 - normal with no monitor aspect ratio criticality
> +                             * 0x20 - for the hard of hearing with no monitor aspect ratio criticality */
> +                            *q++ = (st->disposition & AV_DISPOSITION_HEARING_IMPAIRED) ? 0x20 : 0x10;
> +                            if ((st->codec->extradata_size == 4) && (extradata_copied == 0)) {
> +                                /* support of old 4-byte extradata format */
> +                                memcpy(q, st->codec->extradata, 4); /* composition_page_id and ancillary_page_id */
> +                                extradata_copied += 4;
> +                                q += 4;
> +                            } else {
> +                                put16(&q, 1); /* composition_page_id */
> +                                put16(&q, 1); /* ancillary_page_id */
> +                            }
> +                        }
>                      }
> +
> +                    *len_ptr = q - len_ptr - 1;

is there some check that protects the output array end from being
overwrtten ?

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

You can kill me, but you cannot change the truth.
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