mirror of https://git.ffmpeg.org/ffmpeg.git
better and simpler logic for MPEG muxing - fixed rare MPEG muxing PTS generation bug (stuffing is added in such rare cases) - fixed AC3 payload size generation - generate correct AC3 frame header (need spec checking)
Originally committed as revision 2621 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Fabrice Bellard
parent
6ec87caa70
commit
0dbb48d91e
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@ -24,6 +24,8 @@
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typedef struct {
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uint8_t buffer[MAX_PAYLOAD_SIZE];
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int buffer_ptr;
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int nb_frames; /* number of starting frame encountered (AC3) */
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int frame_start_offset; /* starting offset of the frame + 1 (0 if none) */
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uint8_t id;
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int max_buffer_size; /* in bytes */
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int packet_number;
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@ -33,10 +35,10 @@ typedef struct {
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typedef struct {
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int packet_size; /* required packet size */
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int packet_data_max_size; /* maximum data size inside a packet */
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int packet_number;
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int pack_header_freq; /* frequency (in packets^-1) at which we send pack headers */
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int system_header_freq;
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int system_header_size;
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int mux_rate; /* bitrate in units of 50 bytes/s */
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/* stream info */
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int audio_bound;
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@ -166,6 +168,25 @@ static int put_system_header(AVFormatContext *ctx, uint8_t *buf)
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return size;
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}
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static int get_system_header_size(AVFormatContext *ctx)
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{
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int buf_index, i, private_stream_coded;
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StreamInfo *stream;
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buf_index = 12;
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private_stream_coded = 0;
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for(i=0;i<ctx->nb_streams;i++) {
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stream = ctx->streams[i]->priv_data;
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if (stream->id < 0xc0) {
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if (private_stream_coded)
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continue;
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private_stream_coded = 1;
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}
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buf_index += 3;
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}
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return buf_index;
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}
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static int mpeg_mux_init(AVFormatContext *ctx)
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{
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MpegMuxContext *s = ctx->priv_data;
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@ -182,10 +203,6 @@ static int mpeg_mux_init(AVFormatContext *ctx)
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else
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s->packet_size = 2048;
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/* startcode(4) + length(2) + flags(1) */
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s->packet_data_max_size = s->packet_size - 7;
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if (s->is_mpeg2)
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s->packet_data_max_size -= 2;
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s->audio_bound = 0;
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s->video_bound = 0;
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mpa_id = AUDIO_ID;
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@ -260,6 +277,7 @@ static int mpeg_mux_init(AVFormatContext *ctx)
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stream->start_pts = AV_NOPTS_VALUE;
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stream->start_dts = AV_NOPTS_VALUE;
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}
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s->system_header_size = get_system_header_size(ctx);
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s->last_scr = 0;
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return 0;
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fail:
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@ -279,6 +297,50 @@ static inline void put_timestamp(ByteIOContext *pb, int id, int64_t timestamp)
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put_be16(pb, (uint16_t)((((timestamp) & 0x7fff) << 1) | 1));
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}
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/* return the exact available payload size for the next packet for
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stream 'stream_index'. 'pts' and 'dts' are only used to know if
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timestamps are needed in the packet header. */
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static int get_packet_payload_size(AVFormatContext *ctx, int stream_index,
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int64_t pts, int64_t dts)
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{
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MpegMuxContext *s = ctx->priv_data;
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int buf_index;
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StreamInfo *stream;
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buf_index = 0;
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if (((s->packet_number % s->pack_header_freq) == 0)) {
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/* pack header size */
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if (s->is_mpeg2)
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buf_index += 14;
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else
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buf_index += 12;
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if ((s->packet_number % s->system_header_freq) == 0)
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buf_index += s->system_header_size;
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}
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/* packet header size */
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buf_index += 6;
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if (s->is_mpeg2)
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buf_index += 3;
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if (pts != AV_NOPTS_VALUE) {
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if (dts != AV_NOPTS_VALUE)
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buf_index += 5 + 5;
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else
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buf_index += 5;
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} else {
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if (!s->is_mpeg2)
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buf_index++;
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}
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stream = ctx->streams[stream_index]->priv_data;
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if (stream->id < 0xc0) {
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/* AC3 private data header */
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buf_index += 4;
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}
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return s->packet_size - buf_index;
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}
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/* flush the packet on stream stream_index */
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static void flush_packet(AVFormatContext *ctx, int stream_index,
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int64_t pts, int64_t dts, int64_t scr)
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@ -286,7 +348,8 @@ static void flush_packet(AVFormatContext *ctx, int stream_index,
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MpegMuxContext *s = ctx->priv_data;
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StreamInfo *stream = ctx->streams[stream_index]->priv_data;
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uint8_t *buf_ptr;
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int size, payload_size, startcode, id, len, stuffing_size, i, header_len;
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int size, payload_size, startcode, id, stuffing_size, i, header_len;
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int packet_size;
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uint8_t buffer[128];
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id = stream->id;
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@ -325,20 +388,21 @@ static void flush_packet(AVFormatContext *ctx, int stream_index,
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header_len++;
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}
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payload_size = s->packet_size - (size + 6 + header_len);
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packet_size = s->packet_size - (size + 6);
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payload_size = packet_size - header_len;
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if (id < 0xc0) {
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startcode = PRIVATE_STREAM_1;
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payload_size -= 4;
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} else {
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startcode = 0x100 + id;
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}
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stuffing_size = payload_size - stream->buffer_ptr;
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if (stuffing_size < 0)
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stuffing_size = 0;
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put_be32(&ctx->pb, startcode);
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put_be16(&ctx->pb, payload_size + header_len);
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put_be16(&ctx->pb, packet_size);
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/* stuffing */
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for(i=0;i<stuffing_size;i++)
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put_byte(&ctx->pb, 0xff);
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@ -377,10 +441,8 @@ static void flush_packet(AVFormatContext *ctx, int stream_index,
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if (startcode == PRIVATE_STREAM_1) {
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put_byte(&ctx->pb, id);
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if (id >= 0x80 && id <= 0xbf) {
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/* XXX: need to check AC3 spec */
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put_byte(&ctx->pb, 1);
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put_byte(&ctx->pb, 0);
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put_byte(&ctx->pb, 2);
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put_byte(&ctx->pb, stream->nb_frames);
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put_be16(&ctx->pb, stream->frame_start_offset);
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}
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}
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@ -388,15 +450,10 @@ static void flush_packet(AVFormatContext *ctx, int stream_index,
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put_buffer(&ctx->pb, stream->buffer, payload_size - stuffing_size);
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put_flush_packet(&ctx->pb);
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/* preserve remaining data */
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len = stream->buffer_ptr - payload_size;
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if (len < 0)
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len = 0;
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memmove(stream->buffer, stream->buffer + stream->buffer_ptr - len, len);
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stream->buffer_ptr = len;
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s->packet_number++;
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stream->packet_number++;
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stream->nb_frames = 0;
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stream->frame_start_offset = 0;
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}
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static int mpeg_mux_write_packet(AVFormatContext *ctx, int stream_index,
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@ -405,8 +462,8 @@ static int mpeg_mux_write_packet(AVFormatContext *ctx, int stream_index,
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MpegMuxContext *s = ctx->priv_data;
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AVStream *st = ctx->streams[stream_index];
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StreamInfo *stream = st->priv_data;
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int64_t dts;
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int len;
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int64_t dts, new_start_pts, new_start_dts;
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int len, avail_size;
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/* XXX: system clock should be computed precisely, especially for
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CBR case. The current mode gives at least something coherent */
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@ -422,28 +479,53 @@ static int mpeg_mux_write_packet(AVFormatContext *ctx, int stream_index,
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dts = AV_NOPTS_VALUE;
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/* we assume here that pts != AV_NOPTS_VALUE */
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new_start_pts = stream->start_pts;
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new_start_dts = stream->start_dts;
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if (stream->start_pts == AV_NOPTS_VALUE) {
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stream->start_pts = pts;
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stream->start_dts = dts;
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new_start_pts = pts;
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new_start_dts = dts;
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}
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avail_size = get_packet_payload_size(ctx, stream_index,
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new_start_pts,
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new_start_dts);
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if (stream->buffer_ptr >= avail_size) {
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/* unlikely case: outputing the pts or dts increase the packet
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size so that we cannot write the start of the next
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packet. In this case, we must flush the current packet with
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padding */
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flush_packet(ctx, stream_index,
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stream->start_pts, stream->start_dts, s->last_scr);
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stream->buffer_ptr = 0;
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}
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stream->start_pts = new_start_pts;
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stream->start_dts = new_start_dts;
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stream->nb_frames++;
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if (stream->frame_start_offset == 0)
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stream->frame_start_offset = stream->buffer_ptr;
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while (size > 0) {
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len = s->packet_data_max_size - stream->buffer_ptr;
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avail_size = get_packet_payload_size(ctx, stream_index,
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stream->start_pts,
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stream->start_dts);
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len = avail_size - stream->buffer_ptr;
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if (len > size)
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len = size;
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memcpy(stream->buffer + stream->buffer_ptr, buf, len);
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stream->buffer_ptr += len;
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buf += len;
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size -= len;
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while (stream->buffer_ptr >= s->packet_data_max_size) {
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/* output the packet */
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if (stream->buffer_ptr >= avail_size) {
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/* if packet full, we send it now */
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flush_packet(ctx, stream_index,
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stream->start_pts, stream->start_dts, s->last_scr);
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stream->buffer_ptr = 0;
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/* Make sure only the FIRST pes packet for this frame has
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a timestamp */
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stream->start_pts = AV_NOPTS_VALUE;
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stream->start_dts = AV_NOPTS_VALUE;
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}
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}
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return 0;
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}
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@ -456,8 +538,11 @@ static int mpeg_mux_end(AVFormatContext *ctx)
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/* flush each packet */
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for(i=0;i<ctx->nb_streams;i++) {
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stream = ctx->streams[i]->priv_data;
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while (stream->buffer_ptr > 0) {
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flush_packet(ctx, i, AV_NOPTS_VALUE, AV_NOPTS_VALUE, s->last_scr);
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if (stream->buffer_ptr > 0) {
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/* NOTE: we can always write the remaining data as it was
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tested before in mpeg_mux_write_packet() */
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flush_packet(ctx, i, stream->start_pts, stream->start_dts,
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s->last_scr);
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}
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}
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@ -755,7 +840,7 @@ static int mpegps_read_packet(AVFormatContext *s,
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}
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if (startcode >= 0x1e0 && startcode <= 0x1ef) {
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type = CODEC_TYPE_VIDEO;
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codec_id = CODEC_ID_MPEG1VIDEO;
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codec_id = CODEC_ID_MPEG2VIDEO;
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} else if (startcode >= 0x1c0 && startcode <= 0x1df) {
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type = CODEC_TYPE_AUDIO;
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codec_id = CODEC_ID_MP2;
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@ -994,7 +1079,7 @@ static AVOutputFormat mpeg2vob_mux = {
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"vob",
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sizeof(MpegMuxContext),
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CODEC_ID_MP2,
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CODEC_ID_MPEG1VIDEO,
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CODEC_ID_MPEG2VIDEO,
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mpeg_mux_init,
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mpeg_mux_write_packet,
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mpeg_mux_end,
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