* [FFmpeg-devel] [PATCH] avformat/mpjpegdec: add support for X-Timestamp and X-Framerate headers
@ 2025-11-09 0:38 Vladimir Sobolev via ffmpeg-devel
2025-11-11 3:16 ` [FFmpeg-devel] " Michael Niedermayer via ffmpeg-devel
0 siblings, 1 reply; 2+ messages in thread
From: Vladimir Sobolev via ffmpeg-devel @ 2025-11-09 0:38 UTC (permalink / raw)
To: ffmpeg-devel; +Cc: Vladimir Sobolev
>From 31d73c6774c1ea6d621db57f26439e297cc23c3d Mon Sep 17 00:00:00 2001
From: Vladimir Sobolev <v.sobolev@gmail.com>
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)) {
+ /* 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);
+ }
}
}
@@ -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;
+ }
+
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);
+ pkt->dts = pkt->pts;
+ }
+
return ret;
}
--
2.50.1 (Apple Git-155)
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^ permalink raw reply [flat|nested] 2+ messages in thread
* [FFmpeg-devel] Re: [PATCH] avformat/mpjpegdec: add support for X-Timestamp and X-Framerate headers
2025-11-09 0:38 [FFmpeg-devel] [PATCH] avformat/mpjpegdec: add support for X-Timestamp and X-Framerate headers Vladimir Sobolev via ffmpeg-devel
@ 2025-11-11 3:16 ` Michael Niedermayer via ffmpeg-devel
0 siblings, 0 replies; 2+ messages in thread
From: Michael Niedermayer via ffmpeg-devel @ 2025-11-11 3:16 UTC (permalink / raw)
To: FFmpeg development discussions and patches; +Cc: Michael Niedermayer
[-- Attachment #1.1: Type: text/plain, Size: 7906 bytes --]
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 <v.sobolev@gmail.com>
> 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
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2025-11-09 0:38 [FFmpeg-devel] [PATCH] avformat/mpjpegdec: add support for X-Timestamp and X-Framerate headers Vladimir Sobolev via ffmpeg-devel
2025-11-11 3:16 ` [FFmpeg-devel] " Michael Niedermayer via ffmpeg-devel
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