> 2020年11月25日 下午7:49,Vignesh Ravichandran <vignesh.ravichandra...@gmail.com> 写道: > > We could add a simple check like below to prevent it: > > if (sscanf(ptr, "%d-%d-%dT%d:%d:%d.%lf", &y, &M, &d, &h, &m, &s, &ms) != 7) > { > ret = AVERROR_INVALIDDATA; > goto fail; > } > > Please let me know. Not sure this is better way, what about validate the string of the "#EXT-X-PROGRAM-DATE-TIME” values? > > > Thanks, > Vignesh > > On Wed, Nov 25, 2020 at 11:29 AM Steven Liu <l...@chinaffmpeg.org> wrote: > >> >> >>> 2020年11月25日 下午1:16,Vignesh Ravichandran < >> vignesh.ravichandra...@gmail.com> 写道: >>> >>> Bug ID: 8989 >>> >>> This is is due to the following behavior in the current code: >>> 1. The initial_prog_date_time gets set to the current local time >>> 2. The existing playlist (.m3u8) file gets parsed and the segments >> present are added to the variant stream >>> 3. The new segment is created and added >>> 4. The existing segments and the new segment are written to the playlist >> file. The initial_prog_date_time from point 1 is used for calculating >> "#EXT-X-PROGRAM-DATE-TIME" for the segments, which results in incorrect >> "#EXT-X-PROGRAM-DATE-TIME" values for existing segments >>> >>> The following approach fixes this bug: >>> 1. Add a new variable "discont_program_date_time" of type double to >> HLSSegment struct >>> 2. Store the "EXT-X-PROGRAM-DATE-TIME" value from the existing segments >> in this variable >>> 3. When writing to playlist file if "discont_program_date_time" is set, >> then use that value for "EXT-X-PROGRAM-DATE-TIME" else use the value >> present in vs->initial_prog_date_time >>> >>> Signed-off-by: Vignesh Ravichandran <vignesh.ravichandra...@gmail.com> >>> --- >>> libavformat/hlsenc.c | 35 +++++++++++++++++++++++++++++++---- >>> 1 file changed, 31 insertions(+), 4 deletions(-) >>> >>> diff --git a/libavformat/hlsenc.c b/libavformat/hlsenc.c >>> index cbfd8f7c0d..030a2d3b97 100644 >>> --- a/libavformat/hlsenc.c >>> +++ b/libavformat/hlsenc.c >>> @@ -88,6 +88,7 @@ typedef struct HLSSegment { >>> char iv_string[KEYSIZE*2 + 1]; >>> >>> struct HLSSegment *next; >>> + double discont_program_date_time; >>> } HLSSegment; >>> >>> typedef enum HLSFlags { >>> @@ -1124,6 +1125,7 @@ static int hls_append_segment(struct >> AVFormatContext *s, HLSContext *hls, >>> en->keyframe_size = vs->video_keyframe_size; >>> en->next = NULL; >>> en->discont = 0; >>> + en->discont_program_date_time = 0; >>> >>> if (vs->discontinuity) { >>> en->discont = 1; >>> @@ -1148,7 +1150,8 @@ static int hls_append_segment(struct >> AVFormatContext *s, HLSContext *hls, >>> >>> if (hls->max_nb_segments && vs->nb_entries >= hls->max_nb_segments) { >>> en = vs->segments; >>> - vs->initial_prog_date_time += en->duration; >>> + if (!en->next->discont_program_date_time && >> !en->discont_program_date_time) >>> + vs->initial_prog_date_time += en->duration; >>> vs->segments = en->next; >>> if (en && hls->flags & HLS_DELETE_SEGMENTS && >>> #if FF_API_HLS_WRAP >>> @@ -1182,6 +1185,8 @@ static int parse_playlist(AVFormatContext *s, >> const char *url, VariantStream *vs >>> char line[MAX_URL_SIZE]; >>> const char *ptr; >>> const char *end; >>> + int is_discont_detected = 0; >>> + double discont_program_date_time = 0; >>> >>> if ((ret = ffio_open_whitelist(&in, url, AVIO_FLAG_READ, >>> &s->interrupt_callback, NULL, >>> @@ -1211,6 +1216,7 @@ static int parse_playlist(AVFormatContext *s, >> const char *url, VariantStream *vs >>> } else if (av_strstart(line, "#EXT-X-DISCONTINUITY", &ptr)) { >>> is_segment = 1; >>> vs->discontinuity = 1; >>> + is_discont_detected = 1; >>> } else if (av_strstart(line, "#EXTINF:", &ptr)) { >>> is_segment = 1; >>> vs->duration = atof(ptr); >>> @@ -1236,7 +1242,23 @@ static int parse_playlist(AVFormatContext *s, >> const char *url, VariantStream *vs >>> av_strlcpy(vs->iv_string, ptr, >> sizeof(vs->iv_string)); >>> } >>> } >>> - >>> + } else if (av_strstart(line, "#EXT-X-PROGRAM-DATE-TIME:", &ptr) >> && is_discont_detected) { >>> + struct tm program_date_time; >>> + int y,M,d,h,m,s; >>> + double ms; >>> + sscanf(ptr, "%d-%d-%dT%d:%d:%d.%lf", &y, &M, &d, &h, &m, >> &s, &ms); >> What will happen if I modify the value of “EXT-X-PROGRAM-DATE-TIME” by >> hacker, >> For example: >> #EXT-X-PROGRAM-DATA-TIME: good-morning-ladies-and-gentlemen. >> >>> + >>> + program_date_time.tm_year = y - 1900; >>> + program_date_time.tm_mon = M - 1; >>> + program_date_time.tm_mday = d; >>> + program_date_time.tm_hour = h; >>> + program_date_time.tm_min = m; >>> + program_date_time.tm_sec = s; >>> + program_date_time.tm_isdst = -1; >>> + >>> + discont_program_date_time = mktime(&program_date_time); >>> + discont_program_date_time += (double)(ms / 1000); >>> + is_discont_detected = 0; >>> } else if (av_strstart(line, "#", NULL)) { >>> continue; >>> } else if (line[0]) { >>> @@ -1250,8 +1272,9 @@ static int parse_playlist(AVFormatContext *s, >> const char *url, VariantStream *vs >>> is_segment = 0; >>> new_start_pos = avio_tell(vs->avf->pb); >>> vs->size = new_start_pos - vs->start_pos; >>> - vs->initial_prog_date_time -= vs->duration; // this is >> a previously existing segment >>> ret = hls_append_segment(s, hls, vs, vs->duration, >> vs->start_pos, vs->size); >>> + vs->last_segment->discont_program_date_time = >> discont_program_date_time; >>> + discont_program_date_time += vs->duration; >>> if (ret < 0) >>> goto fail; >>> vs->start_pos = new_start_pos; >>> @@ -1572,7 +1595,11 @@ static int hls_window(AVFormatContext *s, int >> last, VariantStream *vs) >>> ret = ff_hls_write_file_entry(byterange_mode ? hls->m3u8_out : >> vs->out, en->discont, byterange_mode, >>> en->duration, hls->flags & >> HLS_ROUND_DURATIONS, >>> en->size, en->pos, hls->baseurl, >>> - en->filename, prog_date_time_p, >> en->keyframe_size, en->keyframe_pos, hls->flags & HLS_I_FRAMES_ONLY); >>> + en->filename, >>> + en->discont_program_date_time ? >> &en->discont_program_date_time : prog_date_time_p, >>> + en->keyframe_size, >> en->keyframe_pos, hls->flags & HLS_I_FRAMES_ONLY); >>> + if (en->discont_program_date_time) >>> + en->discont_program_date_time -= en->duration; >>> if (ret < 0) { >>> av_log(s, AV_LOG_WARNING, "ff_hls_write_file_entry get >> error\n"); >>> } >>> -- >>> 2.24.2 (Apple Git-127) >>> >>> _______________________________________________ >>> ffmpeg-devel mailing list >>> ffmpeg-devel@ffmpeg.org >>> https://ffmpeg.org/mailman/listinfo/ffmpeg-devel >>> >>> To unsubscribe, visit link above, or email >>> ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe". >> >> Thanks >> >> Steven Liu >> >> >> >> > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel > > To unsubscribe, visit link above, or email > ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
Thanks Steven Liu _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".