From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ffbox0-bg.ffmpeg.org (ffbox0-bg.ffmpeg.org [79.124.17.100]) by master.gitmailbox.com (Postfix) with ESMTPS id 6D6224CABE for ; Tue, 27 May 2025 10:40:49 +0000 (UTC) Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.ffmpeg.org (Postfix) with ESMTP id 5795E68D57C; Tue, 27 May 2025 13:40:45 +0300 (EEST) Received: from 8.mo533.mail-out.ovh.net (8.mo533.mail-out.ovh.net [54.36.140.183]) by ffbox0-bg.ffmpeg.org (Postfix) with ESMTPS id 3548C68CF07 for ; Tue, 27 May 2025 13:40:38 +0300 (EEST) Received: from director3.derp.mail-out.ovh.net (director3.derp.mail-out.ovh.net [152.228.215.222]) by mo533.mail-out.ovh.net (Postfix) with ESMTPS id 4b68Kx43CWz1Z3q; Tue, 27 May 2025 10:40:37 +0000 (UTC) Received: from director3.derp.mail-out.ovh.net (director3.derp.mail-out.ovh.net. [127.0.0.1]) by director3.derp.mail-out.ovh.net (inspect_sender_mail_agent) with SMTP for ; Tue, 27 May 2025 10:40:37 +0000 (UTC) Received: from mta11.priv.ovhmail-u1.ea.mail.ovh.net (unknown [10.108.9.234]) by director3.derp.mail-out.ovh.net (Postfix) with ESMTPS id 4b68Kx1WJ6z5xLB; Tue, 27 May 2025 10:40:37 +0000 (UTC) Received: from mailstore2.priv.ovhmail-u1.ea.mail.ovh.net (unknown [10.2.8.2]) by mta11.priv.ovhmail-u1.ea.mail.ovh.net (Postfix) with ESMTP id AE1E5263BAF; Tue, 27 May 2025 10:40:36 +0000 (UTC) Date: Tue, 27 May 2025 10:40:36 +0000 (UTC) To: ffmpeg-devel@ffmpeg.org Message-ID: <1210481741.184664378.1748342436436.JavaMail.zimbra@orca.pet> In-Reply-To: <20250527102811.369474-1-marcos@orca.pet> References: <20250527102811.369474-1-marcos@orca.pet> MIME-Version: 1.0 X-Originating-IP: [147.156.42.6] Thread-Topic: avformat/webvttdec: improve WebVTT parsing Thread-Index: euTVBre3dUA3AXvnNgAegAV5AgDCBQ== X-Ovh-Tracer-Id: 10855082477476271702 X-VR-SPAMSTATE: OK X-VR-SPAMSCORE: -100 X-VR-SPAMCAUSE: gggruggvucftvghtrhhoucdtuddrgeeffedrtddtgddvtddujeculddtuddrgeefvddrtddtmdcutefuodetggdotefrodftvfcurfhrohhfihhlvgemucfqggfjpdevjffgvefmvefgnecuuegrihhlohhuthemucehtddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenucfjughrpeffhffvvefkjghfufggtgfgihhtsehtjegttddttdejnecuhfhrohhmpeforghrtghoshcuffgvlhcuufholhcuoehmrghrtghoshesohhrtggrrdhpvghtqeenucggtffrrghtthgvrhhnpedvvdelheeuffelveeuieetffegffevieegvddvteehfeeiudegtdehuddtfeevueenucffohhmrghinhepfiefrdhorhhgpdeftggrthdrtggrthenucfkphepuddvjedrtddrtddruddpudegjedrudehiedrgedvrdeinecuvehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehinhgvthepuddvjedrtddrtddruddpmhgrihhlfhhrohhmpehmrghrtghoshesohhrtggrrdhpvghtpdhnsggprhgtphhtthhopedvpdhrtghpthhtohepfhhfmhhpvghgqdguvghvvghlsehffhhmphgvghdrohhrghdprhgtphhtthhopehmrghrtghoshesohhrtggrrdhpvghtpdfovfetjfhoshhtpehmohehfeefmgdpmhhouggvpehsmhhtphhouhht Subject: Re: [FFmpeg-devel] [PATCH] avformat/webvttdec: improve WebVTT parsing X-BeenThere: ffmpeg-devel@ffmpeg.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: FFmpeg development discussions and patches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Marcos Del Sol via ffmpeg-devel Reply-To: FFmpeg development discussions and patches Cc: Marcos Del Sol Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: ffmpeg-devel-bounces@ffmpeg.org Sender: "ffmpeg-devel" Archived-At: List-Archive: List-Post: A note on this change: I found some .vtt files while using yt-dlp that follow a draft version of the WebVTT standard (probably https://www.w3.org/2013/07/webvtt.html) that use "Region:" for regions instead of "REGION", and that was causing the conversion to .srt to fail completely. An example of those files is available at https://statics.3cat.cat/multimedia/vtt/2/4/1745967620742.vtt, which belongs to a state-owned free online streaming service in Spain. While the diff might seem large, I basically moved the current cue parsing to a function because it made error handling much easier. The logic is the exact same. -----Mensaje original----- De: Marcos Para: ffmpeg-devel CC: Marcos Fecha: martes, 27 de mayo de 2025 12:29 CEST Asunto: [PATCH] avformat/webvttdec: improve WebVTT parsing The parser will now strictly check if WebVTT files start with the correct "WEBVTT" marker. Before, files were not checked if they truly started with it. It will also now ignore all non-cue blocks, instead of only a hardcoded list. This is closer to the specification that calls for no action if unknown blocks are encountered. Signed-off-by: Marcos Del Sol Vives --- libavformat/webvttdec.c | 178 ++++++++++++++++++++++------------------ 1 file changed, 98 insertions(+), 80 deletions(-) diff --git a/libavformat/webvttdec.c b/libavformat/webvttdec.c index 6feda1585e..b454b2c1cf 100644 --- a/libavformat/webvttdec.c +++ b/libavformat/webvttdec.c @@ -58,6 +58,79 @@ static int64_t read_ts(const char *s) return AV_NOPTS_VALUE; } +static int webvtt_parse_cue(WebVTTContext *webvtt, AVBPrint *cue, int64_t pos) +{ + int i; + AVPacket *sub; + const char *p, *identifier, *settings; + size_t identifier_len, settings_len; + int64_t ts_start, ts_end; + + p = identifier = cue->str; + + /* optional cue identifier (can be a number like in SRT or some kind of + * chaptering id) */ + for (i = 0; p[i] && p[i] != '\n' && p[i] != '\r'; i++) { + if (!strncmp(p + i, "-->", 3)) { + identifier = NULL; + break; + } + } + if (!identifier) + identifier_len = 0; + else { + identifier_len = strcspn(p, "\r\n"); + p += identifier_len; + if (*p == '\r') + p++; + if (*p == '\n') + p++; + } + + /* cue timestamps */ + if ((ts_start = read_ts(p)) == AV_NOPTS_VALUE) + return AVERROR_INVALIDDATA; + if (!(p = strstr(p, "-->"))) + return AVERROR_INVALIDDATA; + p += 2; + do p++; while (*p == ' ' || *p == '\t'); + if ((ts_end = read_ts(p)) == AV_NOPTS_VALUE) + return AVERROR_INVALIDDATA; + + /* optional cue settings */ + p += strcspn(p, "\n\r\t "); + while (*p == '\t' || *p == ' ') + p++; + settings = p; + settings_len = strcspn(p, "\r\n"); + p += settings_len; + if (*p == '\r') + p++; + if (*p == '\n') + p++; + + /* create packet */ + sub = ff_subtitles_queue_insert(&webvtt->q, p, strlen(p), 0); + if (!sub) + return AVERROR(ENOMEM); + sub->pos = pos; + sub->pts = ts_start; + sub->duration = ts_end - ts_start; + +#define SET_SIDE_DATA(name, type) do { \ + if (name##_len) { \ + uint8_t *buf = av_packet_new_side_data(sub, type, name##_len); \ + if (!buf) \ + return AVERROR(ENOMEM); \ + memcpy(buf, name, name##_len); \ + } \ +} while (0) + + SET_SIDE_DATA(identifier, AV_PKT_DATA_WEBVTT_IDENTIFIER); + SET_SIDE_DATA(settings, AV_PKT_DATA_WEBVTT_SETTINGS); + return 0; +} + static int webvtt_read_header(AVFormatContext *s) { WebVTTContext *webvtt = s->priv_data; @@ -74,13 +147,27 @@ static int webvtt_read_header(AVFormatContext *s) av_bprint_init(&cue, 0, AV_BPRINT_SIZE_UNLIMITED); + res = ff_subtitles_read_chunk(s->pb, &cue); + if (res < 0) { + av_log(s, AV_LOG_ERROR, "Unable to read file header\n"); + goto end; + } + + if (!cue.len) { + av_log(s, AV_LOG_ERROR, "Unable to read file header\n"); + res = AVERROR_EOF; + goto end; + } + + if (!strncmp(cue.str, "\xEF\xBB\xBFWEBVTT", 9) && + !strncmp(cue.str, "WEBVTT", 6)) { + av_log(s, AV_LOG_ERROR, "Invalid file header\n"); + res = AVERROR_INVALIDDATA; + goto end; + } + for (;;) { - int i; - int64_t pos; - AVPacket *sub; - const char *p, *identifier, *settings; - size_t identifier_len, settings_len; - int64_t ts_start, ts_end; + int64_t pos = avio_tell(s->pb); res = ff_subtitles_read_chunk(s->pb, &cue); if (res < 0) @@ -89,81 +176,12 @@ static int webvtt_read_header(AVFormatContext *s) if (!cue.len) break; - p = identifier = cue.str; - pos = avio_tell(s->pb); - - /* ignore header chunk */ - if (!strncmp(p, "\xEF\xBB\xBFWEBVTT", 9) || - !strncmp(p, "WEBVTT", 6) || - !strncmp(p, "STYLE", 5) || - !strncmp(p, "REGION", 6) || - !strncmp(p, "NOTE", 4)) - continue; - - /* optional cue identifier (can be a number like in SRT or some kind of - * chaptering id) */ - for (i = 0; p[i] && p[i] != '\n' && p[i] != '\r'; i++) { - if (!strncmp(p + i, "-->", 3)) { - identifier = NULL; - break; - } - } - if (!identifier) - identifier_len = 0; - else { - identifier_len = strcspn(p, "\r\n"); - p += identifier_len; - if (*p == '\r') - p++; - if (*p == '\n') - p++; + res = webvtt_parse_cue(webvtt, &cue, pos); + if (res < 0) { + if (res != AVERROR_INVALIDDATA) + goto end; + av_log(s, AV_LOG_DEBUG, "Ignoring non-cue block at 0x%"PRIx64"\n", pos); } - - /* cue timestamps */ - if ((ts_start = read_ts(p)) == AV_NOPTS_VALUE) - break; - if (!(p = strstr(p, "-->"))) - break; - p += 2; - do p++; while (*p == ' ' || *p == '\t'); - if ((ts_end = read_ts(p)) == AV_NOPTS_VALUE) - break; - - /* optional cue settings */ - p += strcspn(p, "\n\r\t "); - while (*p == '\t' || *p == ' ') - p++; - settings = p; - settings_len = strcspn(p, "\r\n"); - p += settings_len; - if (*p == '\r') - p++; - if (*p == '\n') - p++; - - /* create packet */ - sub = ff_subtitles_queue_insert(&webvtt->q, p, strlen(p), 0); - if (!sub) { - res = AVERROR(ENOMEM); - goto end; - } - sub->pos = pos; - sub->pts = ts_start; - sub->duration = ts_end - ts_start; - -#define SET_SIDE_DATA(name, type) do { \ - if (name##_len) { \ - uint8_t *buf = av_packet_new_side_data(sub, type, name##_len); \ - if (!buf) { \ - res = AVERROR(ENOMEM); \ - goto end; \ - } \ - memcpy(buf, name, name##_len); \ - } \ -} while (0) - - SET_SIDE_DATA(identifier, AV_PKT_DATA_WEBVTT_IDENTIFIER); - SET_SIDE_DATA(settings, AV_PKT_DATA_WEBVTT_SETTINGS); } ff_subtitles_queue_finalize(s, &webvtt->q); -- 2.34.1 _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".