suppress PTS in packets when not needed (slightly smaller files), fixed PTS generation in some cases, added provision for DTS generation, slightly better SCR generation (initial patch by Michel Bardiaux)

Originally committed as revision 2585 to svn://svn.ffmpeg.org/ffmpeg/trunk
21 years ago · 27a206e031
parent 8a56ac7b89
commit 27a206e031
1 changed files with 103 additions and 31 deletions
--- a/libavformat/mpeg.c
+++ b/libavformat/mpeg.c
@ -19,7 +19,6 @@
 #include "avformat.h"

 #define MAX_PAYLOAD_SIZE 4096
-#define NB_STREAMS 2
 //#define DEBUG_SEEK

 typedef struct {
@ -29,6 +28,7 @@ typedef struct {
    int max_buffer_size; /* in bytes */
    int packet_number;
    int64_t start_pts;
+    int64_t start_dts;
 } StreamInfo;

 typedef struct {
@ -43,6 +43,9 @@ typedef struct {
    int video_bound;
    int is_mpeg2;
    int is_vcd;
+    int scr_stream_index; /* stream from which the system clock is
+                             computed (VBR case) */
+    int64_t last_scr; /* current system clock */
 } MpegMuxContext;

 #define PACK_START_CODE             ((unsigned int)0x000001ba)
@ -181,11 +184,14 @@ static int mpeg_mux_init(AVFormatContext *ctx)
        
    /* startcode(4) + length(2) + flags(1) */
    s->packet_data_max_size = s->packet_size - 7;
+    if (s->is_mpeg2)
+        s->packet_data_max_size -= 2;
    s->audio_bound = 0;
    s->video_bound = 0;
    mpa_id = AUDIO_ID;
    ac3_id = 0x80;
    mpv_id = VIDEO_ID;
+    s->scr_stream_index = -1;
    for(i=0;i<ctx->nb_streams;i++) {
        st = ctx->streams[i];
        stream = av_mallocz(sizeof(StreamInfo));
@ -203,6 +209,9 @@ static int mpeg_mux_init(AVFormatContext *ctx)
            s->audio_bound++;
            break;
        case CODEC_TYPE_VIDEO:
+            /* by default, video is used for the SCR computation */
+            if (s->scr_stream_index == -1)
+                s->scr_stream_index = i;
            stream->id = mpv_id++;
            stream->max_buffer_size = 46 * 1024; 
            s->video_bound++;
@ -211,6 +220,9 @@ static int mpeg_mux_init(AVFormatContext *ctx)
            av_abort();
        }
    }
+    /* if no SCR, use first stream (audio) */
+    if (s->scr_stream_index == -1)
+        s->scr_stream_index = 0;

    /* we increase slightly the bitrate to take into account the
       headers. XXX: compute it exactly */
@ -245,8 +257,10 @@ static int mpeg_mux_init(AVFormatContext *ctx)
        stream = ctx->streams[i]->priv_data;
        stream->buffer_ptr = 0;
        stream->packet_number = 0;
-        stream->start_pts = -1;
+        stream->start_pts = AV_NOPTS_VALUE;
+        stream->start_dts = AV_NOPTS_VALUE;
    }
+    s->last_scr = 0;
    return 0;
 fail:
    for(i=0;i<ctx->nb_streams;i++) {
@ -255,28 +269,37 @@ static int mpeg_mux_init(AVFormatContext *ctx)
    return -ENOMEM;
 }

+static inline void put_timestamp(ByteIOContext *pb, int id, int64_t timestamp)
+{
+    put_byte(pb, 
+             (id << 4) | 
+             (((timestamp >> 30) & 0x07) << 1) | 
+             1);
+    put_be16(pb, (uint16_t)((((timestamp >> 15) & 0x7fff) << 1) | 1));
+    put_be16(pb, (uint16_t)((((timestamp) & 0x7fff) << 1) | 1));
+}
+
 /* flush the packet on stream stream_index */
-static void flush_packet(AVFormatContext *ctx, int stream_index)
+static void flush_packet(AVFormatContext *ctx, int stream_index, 
+                         int64_t pts, int64_t dts, int64_t scr)
 {
    MpegMuxContext *s = ctx->priv_data;
    StreamInfo *stream = ctx->streams[stream_index]->priv_data;
    uint8_t *buf_ptr;
    int size, payload_size, startcode, id, len, stuffing_size, i, header_len;
-    int64_t timestamp;
    uint8_t buffer[128];
    
    id = stream->id;
-    timestamp = stream->start_pts;
    
 #if 0
    printf("packet ID=%2x PTS=%0.3f\n", 
-           id, timestamp / 90000.0);
+           id, pts / 90000.0);
 #endif

    buf_ptr = buffer;
    if (((s->packet_number % s->pack_header_freq) == 0)) {
        /* output pack and systems header if needed */
-        size = put_pack_header(ctx, buf_ptr, timestamp);
+        size = put_pack_header(ctx, buf_ptr, scr);
        buf_ptr += size;
        if ((s->packet_number % s->system_header_freq) == 0) {
            size = put_system_header(ctx, buf_ptr);
@ -288,10 +311,20 @@ static void flush_packet(AVFormatContext *ctx, int stream_index)

    /* packet header */
    if (s->is_mpeg2) {
-        header_len = 8;
+        header_len = 3;
+    } else {
+        header_len = 0;
+    }
+    if (pts != AV_NOPTS_VALUE) {
+        if (dts != AV_NOPTS_VALUE)
+            header_len += 5 + 5;
+        else
+            header_len += 5;
    } else {
-        header_len = 5;
+        if (!s->is_mpeg2)
+            header_len++;
    }
+
    payload_size = s->packet_size - (size + 6 + header_len);
    if (id < 0xc0) {
        startcode = PRIVATE_STREAM_1;
@ -312,15 +345,34 @@ static void flush_packet(AVFormatContext *ctx, int stream_index)

    if (s->is_mpeg2) {
        put_byte(&ctx->pb, 0x80); /* mpeg2 id */
-        put_byte(&ctx->pb, 0x80); /* flags */
-        put_byte(&ctx->pb, 0x05); /* header len (only pts is included) */
+
+        if (pts != AV_NOPTS_VALUE) {
+            if (dts != AV_NOPTS_VALUE) {
+                put_byte(&ctx->pb, 0xc0); /* flags */
+                put_byte(&ctx->pb, header_len - 3);
+                put_timestamp(&ctx->pb, 0x03, pts);
+                put_timestamp(&ctx->pb, 0x01, dts);
+            } else {
+                put_byte(&ctx->pb, 0x80); /* flags */
+                put_byte(&ctx->pb, header_len - 3);
+                put_timestamp(&ctx->pb, 0x02, pts);
+            }
+        } else {
+            put_byte(&ctx->pb, 0x00); /* flags */
+            put_byte(&ctx->pb, header_len - 3);
+        }
+    } else {
+        if (pts != AV_NOPTS_VALUE) {
+            if (dts != AV_NOPTS_VALUE) {
+                put_timestamp(&ctx->pb, 0x03, pts);
+                put_timestamp(&ctx->pb, 0x01, dts);
+            } else {
+                put_timestamp(&ctx->pb, 0x02, pts);
+            }
+        } else {
+            put_byte(&ctx->pb, 0x0f);
+        }
    }
-    put_byte(&ctx->pb, 
-             (0x02 << 4) | 
-             (((timestamp >> 30) & 0x07) << 1) | 
-             1);
-    put_be16(&ctx->pb, (uint16_t)((((timestamp >> 15) & 0x7fff) << 1) | 1));
-    put_be16(&ctx->pb, (uint16_t)((((timestamp) & 0x7fff) << 1) | 1));

    if (startcode == PRIVATE_STREAM_1) {
        put_byte(&ctx->pb, id);
@ -345,7 +397,6 @@ static void flush_packet(AVFormatContext *ctx, int stream_index)

    s->packet_number++;
    stream->packet_number++;
-    stream->start_pts = -1;
 }

 static int mpeg_mux_write_packet(AVFormatContext *ctx, int stream_index,
@ -354,13 +405,28 @@ static int mpeg_mux_write_packet(AVFormatContext *ctx, int stream_index,
    MpegMuxContext *s = ctx->priv_data;
    AVStream *st = ctx->streams[stream_index];
    StreamInfo *stream = st->priv_data;
+    int64_t dts;
    int len;

+    /* XXX: system clock should be computed precisely, especially for
+       CBR case. The current mode gives at least something coherent */
+    if (stream_index == s->scr_stream_index)
+        s->last_scr = pts;
+    
+#if 0
+    printf("%d: pts=%0.3f scr=%0.3f\n", 
+           stream_index, pts / 90000.0, s->last_scr / 90000.0);
+#endif
+    
+    /* XXX: currently no way to pass dts, will change soon */
+    dts = AV_NOPTS_VALUE;
+
+    /* we assume here that pts != AV_NOPTS_VALUE */
+    if (stream->start_pts == AV_NOPTS_VALUE) {
+        stream->start_pts = pts;
+        stream->start_dts = dts;
+    }
    while (size > 0) {
-        /* set pts */
-        if (stream->start_pts == -1) {
-            stream->start_pts = pts;
-        }
        len = s->packet_data_max_size - stream->buffer_ptr;
        if (len > size)
            len = size;
@ -370,9 +436,12 @@ static int mpeg_mux_write_packet(AVFormatContext *ctx, int stream_index,
        size -= len;
        while (stream->buffer_ptr >= s->packet_data_max_size) {
            /* output the packet */
-            if (stream->start_pts == -1)
-                stream->start_pts = pts;
-            flush_packet(ctx, stream_index);
+            flush_packet(ctx, stream_index,
+                         stream->start_pts, stream->start_dts, s->last_scr);
+            /* Make sure only the FIRST pes packet for this frame has
+               a timestamp */
+            stream->start_pts = AV_NOPTS_VALUE;
+            stream->start_dts = AV_NOPTS_VALUE;
        }
    }
    return 0;
@ -380,14 +449,15 @@ static int mpeg_mux_write_packet(AVFormatContext *ctx, int stream_index,

 static int mpeg_mux_end(AVFormatContext *ctx)
 {
+    MpegMuxContext *s = ctx->priv_data;
    StreamInfo *stream;
    int i;

    /* flush each packet */
    for(i=0;i<ctx->nb_streams;i++) {
        stream = ctx->streams[i]->priv_data;
-        if (stream->buffer_ptr > 0) {
-            flush_packet(ctx, i);
+        while (stream->buffer_ptr > 0) {
+            flush_packet(ctx, i, AV_NOPTS_VALUE, AV_NOPTS_VALUE, s->last_scr);
        }
    }

@ -728,12 +798,14 @@ static int mpegps_read_packet(AVFormatContext *s,
        st->codec.bit_rate = st->codec.channels * st->codec.sample_rate * 2;
    }
    av_new_packet(pkt, len);
-    //printf("\nRead Packet ID: %x PTS: %f Size: %d", startcode,
-    //       (float)pts/90000, len);
    get_buffer(&s->pb, pkt->data, pkt->size);
    pkt->pts = pts;
    pkt->dts = dts;
    pkt->stream_index = st->index;
+#if 0
+    printf("%d: pts=%0.3f dts=%0.3f\n",
+           pkt->stream_index, pkt->pts / 90000.0, pkt->dts / 90000.0);
+#endif
    return 0;
 }