[FFmpeg-devel] BUG in use of extradata and extradata_size with dvb subtitles and teletext
Michael Niedermayer
michaelni at gmx.at
Thu Jan 23 23:31:21 CET 2014
On Wed, Jan 22, 2014 at 05:07:37PM +0200, Andriy Lysnevych wrote:
> Please review the updated patch with fixes based on your comments.
>
> Regards,
> Andriy Lysnevych
> mpegts.c | 40 ++++++++++++++++++++++++---
> mpegtsenc.c | 86 ++++++++++++++++++++++++++++++++++++++++++++++--------------
> 2 files changed, 102 insertions(+), 24 deletions(-)
> 2d733a7a4b4575cc0d4b1832bf4cce2a6821379c 0001-correct-DVB-teletext-processing.patch
> From c899d53980a23c132c46e778ac9f15d3897b914b Mon Sep 17 00:00:00 2001
> From: Serhii Marchuk <serhii.marchuk at gmail.com>
> Date: Wed, 22 Jan 2014 10:11:56 +0200
> Subject: mpegts muxer and demuxer: correct DVB teletext processing
>
> * Using extradata by TS demuxer to store values from PMT
> * Using extradata by TS muxer to correctly restore PMT table
> * PES_header_data_length should be always 0x24 for DVB teletext,
> according to DVB standard
> * Support of multiple languages in one DVB teletext stream:
> comma separated language codes in metadata "language" field
>
> The patch fixes #2223 ticket.
> ---
> libavformat/mpegts.c | 40 ++++++++++++++++++++---
> libavformat/mpegtsenc.c | 86 ++++++++++++++++++++++++++++++++++++++-----------
> 2 files changed, 102 insertions(+), 24 deletions(-)
>
> diff --git a/libavformat/mpegts.c b/libavformat/mpegts.c
> index db380ca..3d32f9f 100644
> --- a/libavformat/mpegts.c
> +++ b/libavformat/mpegts.c
> @@ -1470,11 +1470,41 @@ int ff_parse_mpeg2_descriptor(AVFormatContext *fc, AVStream *st, int stream_type
> }
> break;
> case 0x56: /* DVB teletext descriptor */
> - language[0] = get8(pp, desc_end);
> - language[1] = get8(pp, desc_end);
> - language[2] = get8(pp, desc_end);
> - language[3] = 0;
> - av_dict_set(&st->metadata, "language", language, 0);
> + {
> + uint8_t *extradata = NULL;
> + int language_count = desc_len / 5;
> +
> + if (desc_len > 0 && desc_len % 5 != 0)
> + return AVERROR_INVALIDDATA;
> +
> + if (language_count > 0) {
> + if (st->codec->extradata == NULL) {
> + if (ff_alloc_extradata(st->codec, language_count * 2)) {
> + return AVERROR(ENOMEM);
> + }
> + }
> +
> + if (st->codec->extradata_size < language_count * 2)
> + return AVERROR_INVALIDDATA;
> +
> + extradata = st->codec->extradata;
> +
> + for (i = 0; i < language_count; i++) {
> + language[i * 4 + 0] = get8(pp, desc_end);
> + language[i * 4 + 1] = get8(pp, desc_end);
> + language[i * 4 + 2] = get8(pp, desc_end);
> + language[i * 4 + 3] = ',';
> +
> + memcpy(extradata, *pp, 2);
> + extradata += 2;
> +
> + *pp += 2;
> + }
> +
> + language[i * 4 - 1] = 0;
> + av_dict_set(&st->metadata, "language", language, 0);
> + }
> + }
> break;
> case 0x59: /* subtitling descriptor */
> language[0] = get8(pp, desc_end);
just wanted to apply but
this produces:
Stream #0:17[0x899](ger,ger): Subtitle: dvb_teletext ([6][0][0][0] / 0x0006)
that is the same language twice
is that intended ?
also please add a check that the language array is big enough
ATM it is but thats just because its litterally hardcoded length is
sufficient for the current maximal language_count and max number of
bytes written.
also please split the mpegts and mpegtsenc parts into seperate patches
(i can split it too when applying if you prefer)
[...]
--
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
Observe your enemies, for they first find out your faults. -- Antisthenes
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