[Ffmpeg-devel] mpeg transport streams

Marcus Hunger marcus.hunger
Fri May 27 12:54:43 CEST 2005


Hi list, hi Eric,

I'm also working on creating standard-conform mpegts using ffmpeg. The
submitted patch has some issues which I already solved.

e.g.:	frames getting bigger than 2^16 bytes (pes_packet_length)
 allowing b-frames
 keeping constant pcr-interval

The results seem to be quite correct. At least that's what Dektec's
StreamXpert says. However, the changes I made are still not ready for
merging into ffmpeg.

Attached you will find two patches which hopefully give you a picture
of my work. I am interested in a discussion of how these could be
merged into cvs.

best regards,

Marcus Hunger
MUGLER AG
Entwicklung
E-mail: marcus.hunger at mugler.de
Tel. +49-3723-747-183
Fax: +49-3723-747-198

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--- /home/marcus/local/software/FFMpeg-20050322.orig/libavformat/mpegts.h	2004-07-14 03:32:14.000000000 +0200
+++ mpegts.h	2005-05-20 16:13:44.000000000 +0200
@@ -25,9 +25,11 @@
 /* pids */
 #define PAT_PID                 0x0000
 #define SDT_PID                 0x0011
+#define CAT_PID			0x0001
 
 /* table ids */
 #define PAT_TID   0x00
+#define CAT_TID   0x01
 #define PMT_TID   0x02 
 #define SDT_TID   0x42
 
@@ -44,10 +46,115 @@
 #define STREAM_TYPE_AUDIO_AC3       0x81
 #define STREAM_TYPE_AUDIO_DTS       0x8a
 
+/** 
+ * 1.0 second at 24Mbit/s
+ * FIXME: the dvb-standard defines a maximum-interval for sdt of 2 seconds
+ */
+#define MAX_SCAN_PACKETS 32000
+
+/* maximum size in which we look for synchronisation if
+   synchronisation is lost */
+#define MAX_RESYNC_SIZE 4096
+
+
+enum MpegTSFilterType {
+    MPEGTS_PES,
+    MPEGTS_SECTION,
+};
+
+typedef void PESCallback(void *opaque, const uint8_t *buf, int len, int is_start);
+
+typedef struct MpegTSPESFilter {
+    PESCallback *pes_cb;
+    void *opaque;
+} MpegTSPESFilter;
+
+typedef void SectionCallback(void *opaque, const uint8_t *buf, int len);
+
+typedef void SetServiceCallback(void *opaque, int ret);
+
+typedef struct MpegTSSectionFilter {
+    int section_index;
+    int section_h_size;
+    uint8_t *section_buf;
+    int check_crc:1;
+    int end_of_section_reached:1;
+    SectionCallback *section_cb;
+    void *opaque;
+
+} MpegTSSectionFilter;
+
+typedef struct MpegTSSection {
+    int pid;
+    int cc;
+    void (*write_packet)(struct MpegTSSection *s, const uint8_t *packet);
+    void *opaque;
+} MpegTSSection;
+
+typedef struct MpegTSFilter {
+    int pid;
+    int last_cc;
+    enum MpegTSFilterType type;
+    union {
+        MpegTSPESFilter pes_filter;
+        MpegTSSectionFilter section_filter;
+    } u;
+} MpegTSFilter;
+
+/*
+ * unified with MpegTSService of mpegtsenc.c
+ */
+typedef struct MpegTSService {
+    int last_cc; /* last cc code (-1 if first packet) */
+    MpegTSSection pmt; /* MPEG2 pmt table context */
+    int pcr_pid;
+    int sid;           /* service ID */
+    int running:1;
+    char *provider_name;
+    char *name;
+} MpegTSService;
+
+struct MpegTSContext {
+    /* user data */
+    AVFormatContext *stream;
+    int raw_packet_size; /* raw packet size, including FEC if present */
+    int auto_guess; /* if true, all pids are analized to find streams */
+    int set_service_ret;
+
+    int mpeg2ts_raw;  /* force raw MPEG2 transport stream output, if possible */
+    int mpeg2ts_compute_pcr; /* compute exact PCR for each transport stream packet */
+
+    /* used to estimate the exact PCR */
+    int64_t cur_pcr;
+    int pcr_incr;
+    int pcr_pid;
+    
+    /* data needed to handle file based ts */
+    int stop_parse; /* stop parsing loop */
+    AVPacket *pkt; /* packet containing av data */
+
+    /******************************************/
+    /* private mpegts data */
+    /* scan context */
+    MpegTSFilter *sdt_filter;
+    int nb_services;
+    MpegTSService **services;
+    
+    /* set service context (XXX: allocated it ?) */
+    SetServiceCallback *set_service_cb;
+    void *set_service_opaque;
+    MpegTSFilter *pat_filter;
+    MpegTSFilter *pmt_filter;
+    int req_sid;
+
+    MpegTSFilter *pids[NB_PID_MAX];
+};
+
+typedef struct MpegTSContext MpegTSContext;
+static int add_pes_stream(MpegTSContext *ts, int pid, int stream_type);
 unsigned int mpegts_crc32(const uint8_t *data, int len);
 extern AVOutputFormat mpegts_mux;
 
-typedef struct MpegTSContext MpegTSContext;
 
 MpegTSContext *mpegts_parse_open(AVFormatContext *s);
 int mpegts_parse_packet(MpegTSContext *ts, AVPacket *pkt,



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