[FFmpeg-devel] [PATCH] avformat/hls: Fixes overwriting existing #EXT-X-PROGRAM-DATE-TIME value in HLS playlist Bug ID: 8989
Vignesh Ravichandran
vignesh.ravichandran02 at gmail.com
Fri Nov 27 08:36:38 EET 2020
av_isdigit seems to only check if the integer is from 0 to 9. So values
above 9 would fail the check, for example: 2020 would fail the check. Also,
we will not be able to use av_isdigit for checking the double value.
On Fri, Nov 27, 2020 at 7:41 AM Steven Liu <lq at chinaffmpeg.org> wrote:
>
>
> > 2020年11月26日 下午10:21，Vignesh Ravichandran <
> vignesh.ravichandran02 at gmail.com> 写道：
> >
> > 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.ravichandran02 at gmail.com>
> > ---
> > libavformat/hlsenc.c | 83 ++++++++++++++++++++++++++++++++++++++++++--
> > 1 file changed, 80 insertions(+), 3 deletions(-)
> >
> > diff --git a/libavformat/hlsenc.c b/libavformat/hlsenc.c
> > index cbfd8f7c0d..9346b2cfea 100644
> > --- a/libavformat/hlsenc.c
> > +++ b/libavformat/hlsenc.c
> > @@ -25,6 +25,10 @@
> > #include <stdint.h>
> > #if HAVE_UNISTD_H
> > #include <unistd.h>
> > +#include <string.h>
> > +#include <errno.h>
> > +#include <limits.h>
> > +#include <math.h>
> > #endif
> >
> > #if CONFIG_GCRYPT
> > @@ -88,6 +92,7 @@ typedef struct HLSSegment {
> > char iv_string[KEYSIZE*2 + 1];
> >
> > struct HLSSegment *next;
> > + double discont_program_date_time;
> > } HLSSegment;
> >
> > typedef enum HLSFlags {
> > @@ -1124,6 +1129,7 @@ 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 +1154,8 @@ 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
> > @@ -1173,6 +1180,44 @@ static int hls_append_segment(struct
> AVFormatContext *s, HLSContext *hls,
> > return 0;
> > }
> >
> > +static int check_program_date_time(const char *prog_date_time) {
> > + char s[strlen(prog_date_time)], *sptr0, *sptr1, *sptr2, *sptr3;
> > + char *err = NULL;
> > + char *arr[6] = {NULL};
> > + int i = 0;
> > + av_strlcpy(s, prog_date_time, strlen(prog_date_time));
> > + char *p = strtok_r(strtok_r(s, "+", &sptr0), "T", &sptr1);
> > + while (p) {
> > + char *q = strtok_r(p, "-", &sptr2);
> > + while (q) {
> > + char *r = strtok_r(q, ":", &sptr3);
> > + while (r) {
> > + arr[i] = r;
> > + i++;
> > + r = strtok_r(NULL, ":", &sptr3);
> > + }
> > + q = strtok_r(NULL, "-", &sptr2);
> > + }
> > + p = strtok_r(NULL, "T", &sptr1);
> > + }
> > +
> > + for (i=0; i < 5; i++) {
> > + errno=0;
> > + long number = strtol(arr[i], &err, 10);
> > + if((arr[i] == err) || (errno == ERANGE && number == LONG_MIN)
> || (errno == ERANGE && number == LONG_MAX)
> > + || (errno == EINVAL) || (errno != 0 && number == 0) ||
> (errno == 0 && arr[i] && *err != 0))
> What about use av_isdigit to check them?
> > + return AVERROR_INVALIDDATA;
> > + }
> > +
> > + errno=0;
> > + double number = strtod(arr[i], &err);
> > + if((arr[i] == err) || (errno == ERANGE && number == HUGE_VALF) ||
> (errno == ERANGE && number == HUGE_VALL)
> > + || (errno == EINVAL) || (errno != 0 && number == 0) || (errno
> == 0 && arr[i] && *err != 0))
> > + return AVERROR_INVALIDDATA;
> > +
> > + return 0;
> > +}
> > +
> > static int parse_playlist(AVFormatContext *s, const char *url,
> VariantStream *vs)
> > {
> > HLSContext *hls = s->priv_data;
> > @@ -1182,6 +1227,8 @@ 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 +1258,7 @@ 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 +1284,31 @@ 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)) {
> > + struct tm program_date_time;
> > + int y,M,d,h,m,s;
> > + double ms;
> > +
> > + if (check_program_date_time(ptr) != 0) {
> > + av_log(hls, AV_LOG_VERBOSE,
> > + "Found invalid program date time %s when parsing
> playlist. "
> > + "Current and subsequent existing segments will
> be ignored", ptr);
> > + ret = AVERROR_INVALIDDATA;
> > + goto fail;
> > + }
> >
> > + sscanf(ptr, "%d-%d-%dT%d:%d:%d.%lf", &y, &M, &d, &h, &m,
> &s, &ms);
> > + 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 +1322,9 @@ 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 +1645,11 @@ 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)
> >
> > _______________________________________________
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> >
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>
> Thanks
>
> Steven Liu
>
>
>
>
>
>
>
>
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