Hi Vladimir On Sun, Nov 09, 2025 at 02:38:56AM +0200, Vladimir Sobolev via ffmpeg-devel wrote: > >From 31d73c6774c1ea6d621db57f26439e297cc23c3d Mon Sep 17 00:00:00 2001 > From: Vladimir Sobolev <[email protected]> > Date: Sun, 9 Nov 2025 02:28:13 +0200 > Subject: [PATCH] avformat/mpjpegdec: add support for X-Timestamp and > X-Framerate headers > > Add support for parsing X-Timestamp and X-Framerate headers from > HTTP multipart MJPEG streams. These headers allow servers to provide > accurate timestamps and framerate information for each frame. > > Changes: > - Parse X-Timestamp header (in seconds) and set packet PTS/DTS > - Parse X-Framerate/X-FrameRate header and update stream framerate > - Maintain backward compatibility (defaults to 25 fps if not provided) > - Add debug logging for parsed header values > > This enables proper timestamp handling for MJPEG streams that provide > timing information in HTTP headers, improving synchronization accuracy. > --- > libavformat/mpjpegdec.c | 69 ++++++++++++++++++++++++++++++++++++++--- > 1 file changed, 65 insertions(+), 4 deletions(-) > > diff --git a/libavformat/mpjpegdec.c b/libavformat/mpjpegdec.c > index 125b17585e..c90d7a2ad4 100644 > --- a/libavformat/mpjpegdec.c > +++ b/libavformat/mpjpegdec.c > @@ -22,6 +22,9 @@ > #include "libavutil/avstring.h" > #include "libavutil/mem.h" > #include "libavutil/opt.h" > +#include "libavutil/parseutils.h" > +#include "libavutil/eval.h" > +#include "libavutil/intfloat.h" > > #include "avformat.h" > #include "demux.h" > @@ -34,6 +37,11 @@ typedef struct MPJPEGDemuxContext { > char *searchstr; > int searchstr_len; > int strict_mime_boundary; > + AVRational framerate; /* framerate from X-Framerate header */ > + int64_t timestamp; /* timestamp from X-Timestamp header */ > + int has_timestamp; /* flag indicating if timestamp was set */ > + int framerate_set; /* flag indicating if framerate was set in > header */ > + int framerate_applied; /* flag indicating if framerate was > applied to stream */ > } MPJPEGDemuxContext; > > static void trim_right(char *p) > @@ -97,7 +105,8 @@ static int split_tag_value(char **tag, char **value, char > *line) > static int parse_multipart_header(AVIOContext *pb, > int* size, > const char* expected_boundary, > - void *log_ctx); > + void *log_ctx, > + MPJPEGDemuxContext *mpjpeg); > > static int mpjpeg_read_close(AVFormatContext *s) > { > @@ -118,7 +127,7 @@ static int mpjpeg_read_probe(const AVProbeData *p) > > ffio_init_read_context(&pb, p->buf, p->buf_size); > > - ret = (parse_multipart_header(&pb.pub, &size, "--", NULL) >= 0) ? > AVPROBE_SCORE_MAX : 0; > + ret = (parse_multipart_header(&pb.pub, &size, "--", NULL, NULL) >= 0) ? > AVPROBE_SCORE_MAX : 0; > > return ret; > } > @@ -146,6 +155,12 @@ static int mpjpeg_read_header(AVFormatContext *s) > st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO; > st->codecpar->codec_id = AV_CODEC_ID_MJPEG; > > + /* Default framerate is 25 fps, will be updated from headers if > available */ > + MPJPEGDemuxContext *mpjpeg = s->priv_data; > + mpjpeg->framerate = (AVRational){25, 1}; > + mpjpeg->framerate_set = 0; > + mpjpeg->framerate_applied = 0; > + mpjpeg->has_timestamp = 0; > avpriv_set_pts_info(st, 60, 1, 25); > > avio_seek(s->pb, pos, SEEK_SET); > @@ -167,7 +182,8 @@ static int parse_content_length(const char *value) > static int parse_multipart_header(AVIOContext *pb, > int* size, > const char* expected_boundary, > - void *log_ctx) > + void *log_ctx, > + MPJPEGDemuxContext *mpjpeg) > { > char line[128]; > int found_content_type = 0; > @@ -235,6 +251,33 @@ static int parse_multipart_header(AVIOContext *pb, > av_log(log_ctx, AV_LOG_WARNING, > "Invalid Content-Length value : %s\n", > value); > + } else if (mpjpeg && !av_strcasecmp(tag, "X-Timestamp")) { > + double ts = av_strtod(value, NULL);
> + if (!isnan(ts) && isfinite(ts)) {
nan is not finite
> + /* X-Timestamp is in seconds, convert to AV_TIME_BASE */
> + mpjpeg->timestamp = (int64_t)(ts * AV_TIME_BASE);
> + mpjpeg->has_timestamp = 1;
> + if (log_ctx)
> + av_log(log_ctx, AV_LOG_DEBUG,
> + "Parsed X-Timestamp: %s -> %"PRId64" (%.6f
> seconds)\n",
> + value, mpjpeg->timestamp, ts);
> + } else if (log_ctx) {
> + av_log(log_ctx, AV_LOG_WARNING,
> + "Invalid X-Timestamp value : %s\n", value);
> + }
> + } else if (mpjpeg && (!av_strcasecmp(tag, "X-Framerate") ||
> !av_strcasecmp(tag, "X-FrameRate"))) {
> + AVRational fps = {0};
> + if (av_parse_video_rate(&fps, value) >= 0 && fps.num > 0 &&
> fps.den > 0) {
> + mpjpeg->framerate = fps;
> + mpjpeg->framerate_set = 1;
> + if (log_ctx)
> + av_log(log_ctx, AV_LOG_DEBUG,
> + "Parsed X-Framerate: %s -> %d/%d fps\n",
> + value, fps.num, fps.den);
> + } else if (log_ctx) {
> + av_log(log_ctx, AV_LOG_WARNING,
> + "Invalid X-Framerate value : %s\n", value);
> + }
all the if(log_ctx) looks wierd i dont think log_ctx is ever NULL in this code
thats under if(mpjpeg)
> }
> }
>
> @@ -311,10 +354,21 @@ static int mpjpeg_read_packet(AVFormatContext *s,
> AVPacket *pkt)
> mpjpeg->searchstr_len = strlen(mpjpeg->searchstr);
> }
>
> - ret = parse_multipart_header(s->pb, &size, mpjpeg->boundary, s);
> + /* Reset timestamp flag for each packet */
> + mpjpeg->has_timestamp = 0;
> +
> + ret = parse_multipart_header(s->pb, &size, mpjpeg->boundary, s, mpjpeg);
> if (ret < 0)
> return ret;
>
> + /* Update framerate if it was set in header and hasn't been applied yet
> */
> + if (mpjpeg->framerate_set && !mpjpeg->framerate_applied && s->nb_streams
> > 0) {
> + AVStream *st = s->streams[0];
> + st->avg_frame_rate = mpjpeg->framerate;
> + avpriv_set_pts_info(st, 60, mpjpeg->framerate.den,
> mpjpeg->framerate.num);
> + mpjpeg->framerate_applied = 1;
> + }
this looks wrong
* you should not set the timebase more than once. it was already set to 1/25
* the average framerate can only match the 1/timebase for "constant fps"
which is the opposit of what this patch is trying to do
> +
> if (size > 0) {
> /* size has been provided to us in MIME header */
> ret = av_get_packet(s->pb, pkt, size);
> @@ -353,6 +407,13 @@ static int mpjpeg_read_packet(AVFormatContext *s,
> AVPacket *pkt)
> }
> }
>
> + /* Set timestamp from X-Timestamp header if available */
> + if (ret >= 0 && mpjpeg->has_timestamp && s->nb_streams > 0) {
> + AVStream *st = s->streams[0];
> + pkt->pts = av_rescale_q(mpjpeg->timestamp, AV_TIME_BASE_Q,
> st->time_base);
rescaling timestamps suggests you set the timebase wrong
thx
[...]
--
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
What does censorship reveal? It reveals fear. -- Julian Assange
signature.asc
Description: PGP signature
_______________________________________________ ffmpeg-devel mailing list -- [email protected] To unsubscribe send an email to [email protected]
