mp4_module doubt
liubin
yurnerola at gmail.com
Tue May 20 07:45:31 UTC 2014
Hi:
It’s really so nice of u guys to help solve this problem.
Actually ,i tried the patch. Find two little bug:
1.start_time is badly used ,may anther var should be declared.
2.
>
> start_time += (sample - start_sample) * duration;
This entry ,maybe we forget the first part. start_sample is in this entry already.
Thanks again!
在 2014年5月19日，下午8:02，Roman Arutyunyan <arut at nginx.com> 写道：
>
> On 19 May 2014, at 04:56, 刘斌 <yurnerola at gmail.com> wrote:
>
>> Hello,
>> I'm just reading this module and wandering if we can reduce flow
>> from nginx by align start time to key frames.Our company is a video
>> website from China.And i want to know does it make sense to do this.
>
> Here’s the patch solving your problem. Currently there are no plans to
> add this to upstream but that can change. It would be nice to hear your
> feedback. Here’s an example of “mp4_align_start” directive added by
> the patch.
>
> location /mp4 {
> mp4;
> mp4_align_start on;
> root /tmp/;
> }
>
> # HG changeset patch
> # User Roman Arutyunyan <arut at nginx.com>
> # Date 1400496445 -14400
> # Mon May 19 14:47:25 2014 +0400
> # Node ID fccafb910a3361e3e2d6ca8afd6edfb576444997
> # Parent 3a48775f1535fe37cd9c034d92c5a5e9ae208c1e
> Mp4: align start to video key frame.
>
> The new directive mp4_align_start adjusts start time to make
> the result mp4 start with a key frame. This makes sense for
> some players displaying garbage until the first key frame.
>
> diff -r 3a48775f1535 -r fccafb910a33 src/http/modules/ngx_http_mp4_module.c
> --- a/src/http/modules/ngx_http_mp4_module.c Tue Apr 29 12:28:41 2014 +0400
> +++ b/src/http/modules/ngx_http_mp4_module.c Mon May 19 14:47:25 2014 +0400
> @@ -43,6 +43,7 @@
> typedef struct {
> size_t buffer_size;
> size_t max_buffer_size;
> + ngx_flag_t align_start;
> } ngx_http_mp4_conf_t;
>
>
> @@ -303,6 +304,8 @@ static ngx_int_t ngx_http_mp4_update_co6
> ngx_http_mp4_trak_t *trak);
> static void ngx_http_mp4_adjust_co64_atom(ngx_http_mp4_file_t *mp4,
> ngx_http_mp4_trak_t *trak, off_t adjustment);
> +static ngx_int_t ngx_http_mp4_align_start(ngx_http_mp4_file_t *mp4,
> + ngx_http_mp4_trak_t *trak);
>
> static char *ngx_http_mp4(ngx_conf_t *cf, ngx_command_t *cmd, void *conf);
> static void *ngx_http_mp4_create_conf(ngx_conf_t *cf);
> @@ -332,6 +335,13 @@ static ngx_command_t ngx_http_mp4_comma
> offsetof(ngx_http_mp4_conf_t, max_buffer_size),
> NULL },
>
> + { ngx_string("mp4_align_start"),
> + NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
> + ngx_conf_set_flag_slot,
> + NGX_HTTP_LOC_CONF_OFFSET,
> + offsetof(ngx_http_mp4_conf_t, align_start),
> + NULL },
> +
> ngx_null_command
> };
>
> @@ -742,6 +752,14 @@ ngx_http_mp4_process(ngx_http_mp4_file_t
> end_offset = 0;
> trak = mp4->trak.elts;
>
> + if (conf->align_start) {
> + for (i = 0; i < mp4->trak.nelts; i++) {
> + if (ngx_http_mp4_align_start(mp4, &trak[i]) == NGX_OK) {
> + break;
> + }
> + }
> + }
> +
> for (i = 0; i < mp4->trak.nelts; i++) {
>
> if (ngx_http_mp4_update_stts_atom(mp4, &trak[i]) != NGX_OK) {
> @@ -3457,6 +3475,110 @@ ngx_http_mp4_adjust_co64_atom(ngx_http_m
> }
>
>
> +static ngx_int_t
> +ngx_http_mp4_align_start(ngx_http_mp4_file_t *mp4, ngx_http_mp4_trak_t *trak)
> +{
> + uint32_t count, duration, sample, start_sample,
> + *stss_entry, *stss_end;
> + uint64_t start_time;
> + ngx_buf_t *stts_data, *stss_data;
> + ngx_mp4_stts_entry_t *stts_entry, *stts_end;
> +
> + stss_data = trak->out[NGX_HTTP_MP4_STSS_DATA].buf;
> + if (stss_data == NULL) {
> + return NGX_AGAIN;
> + }
> +
> + stts_data = trak->out[NGX_HTTP_MP4_STTS_DATA].buf;
> + if (stts_data == NULL) {
> + return NGX_AGAIN;
> + }
> +
> + ngx_log_debug0(NGX_LOG_DEBUG_HTTP, mp4->file.log, 0, "align start");
> +
> + start_time = (uint64_t) mp4->start * trak->timescale / 1000;
> + start_sample = 0;
> +
> + stts_entry = (ngx_mp4_stts_entry_t *) stts_data->pos;
> + stts_end = (ngx_mp4_stts_entry_t *) stts_data->last;
> +
> + while (stts_entry < stts_end) {
> + count = ngx_mp4_get_32value(stts_entry->count);
> + duration = ngx_mp4_get_32value(stts_entry->duration);
> +
> + ngx_log_debug3(NGX_LOG_DEBUG_HTTP, mp4->file.log, 0,
> + "time:%uL, count:%uD, duration:%uD",
> + start_time, count, duration);
> +
> + if (start_time < (uint64_t) count * duration) {
> + start_sample += (ngx_uint_t) (start_time / duration);
> + goto found_stts;
> + }
> +
> + start_sample += count;
> + start_time -= count * duration;
> + stts_entry++;
> + }
> +
> + ngx_log_debug0(NGX_LOG_DEBUG_HTTP, mp4->file.log, 0, "out of stts samples");
> +
> + return NGX_AGAIN;
> +
> +found_stts:
> +
> + stss_entry = (uint32_t *) stss_data->pos;
> + stss_end = (uint32_t *) stss_data->last;
> +
> + while (stss_entry < stss_end) {
> + sample = ngx_mp4_get_32value(stss_entry);
> +
> + ngx_log_debug1(NGX_LOG_DEBUG_HTTP, mp4->file.log, 0,
> + "sync:%uD", sample);
> +
> + if (sample >= start_sample + 1) {
> + sample--;
> + goto found_stss;
> + }
> +
> + stss_entry++;
> + }
> +
> + ngx_log_debug0(NGX_LOG_DEBUG_HTTP, mp4->file.log, 0, "out of stss samples");
> +
> + return NGX_AGAIN;
> +
> +found_stss:
> +
> + while (stts_entry < stts_end) {
> + count = ngx_mp4_get_32value(stts_entry->count);
> + duration = ngx_mp4_get_32value(stts_entry->duration);
> +
> + ngx_log_debug3(NGX_LOG_DEBUG_HTTP, mp4->file.log, 0,
> + "time:%uL, count:%uD, duration:%uD",
> + start_time, count, duration);
> +
> + if (start_sample + count >= sample) {
> + start_time += (sample - start_sample) * duration;
> + mp4->start = (uint64_t) start_time * 1000 / trak->timescale;
> +
> + ngx_log_debug2(NGX_LOG_DEBUG_HTTP, mp4->file.log, 0,
> + "aligned start:%ui, samples:%uD",
> + mp4->start, sample - start_sample);
> +
> + return NGX_OK;
> + }
> +
> + start_sample += count;
> + start_time -= count * duration;
> + stts_entry++;
> + }
> +
> + ngx_log_debug0(NGX_LOG_DEBUG_HTTP, mp4->file.log, 0, "out of stts samples");
> +
> + return NGX_AGAIN;
> +}
> +
> +
> static char *
> ngx_http_mp4(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
> {
> @@ -3481,6 +3603,7 @@ ngx_http_mp4_create_conf(ngx_conf_t *cf)
>
> conf->buffer_size = NGX_CONF_UNSET_SIZE;
> conf->max_buffer_size = NGX_CONF_UNSET_SIZE;
> + conf->align_start = NGX_CONF_UNSET;
>
> return conf;
> }
> @@ -3495,6 +3618,7 @@ ngx_http_mp4_merge_conf(ngx_conf_t *cf,
> ngx_conf_merge_size_value(conf->buffer_size, prev->buffer_size, 512 * 1024);
> ngx_conf_merge_size_value(conf->max_buffer_size, prev->max_buffer_size,
> 10 * 1024 * 1024);
> + ngx_conf_merge_value(conf->align_start, prev->align_start, 0);
>
> return NGX_CONF_OK;
> }
>
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